Gas turbine

ABSTRACT

A gas turbine comprises a compressor for compressing a gas supplied therein and discharging the compressed gas, a combustor in which the discharged gas from the compressor and a fuel are combusted, a turbine to be driven by a combustion gas from the combustor, and an injection unit which injects water into the gas to be supplied to the compressor, thereby lowering the temperature of the gas to be introduced into the compressor than the atmospheric temperature, and causing water droplets having been injected in the gas and within the compressor to be vaporized while flowing down therein, wherein the quantity of water spray injection is controlled while monitoring operational conditions of the gas turbine.

BACKGROUND OF THE INVENTION

[0001] The present invention relates to a gas turbine and moreparticularly, to a gas turbine which injects water droplets into anintake air of a compressor of the gas turbine.

[0002] A conventional gas turbine is caused to drop its output in asummer season when the temperature increases, therefore, variousarrangements have been proposed as a method to recover the droppedoutput.

[0003] JP-A Laid-Open No. 7-97933, JU No. 61-37794, or JP-A Laid-OpenNo. 5-195809 disclose that the intake air of the compressor is cooled.

[0004] Further, JP-A Laid-Open No. 61-283723 discloses that water issupplied from the inlet of the compressor and from the intermediatestage of the compressor in a combined system of a gassification furnaceand a gas turbine.

[0005] Further, JU-A No. 56-43433 discloses that a supply port throughwhich to supply water droplets is provided in its compressor, and JP-ANo. 2-211331 discloses a gas turbine which is provided with two types ofcompressors of a high pressure and a low pressure, and an intermediatecooler which is provided between these two types of compressors. Stillfurther, JP-A No. 6-10702 discloses a technique to inject water into anintermediate section between an upper-stream compressor stage and adown-stream compressor stage in a compressor group having a plurality ofcompressor stages in order to reduce power consumption.

[0006] However, what are disclosed by these related arts of JP-A No.7-97933, JU No. 61-37794 or JP-A No. 5-195809 are addressed simply todropping temperatures of intake air to be admitted into the compressorso as to be able to improve its output. JP-A No. 61-283723 merelydiscloses vaporization of water droplets in the compressor andutilization thereof as a medium to cool the turbine blades, and as aconsequence, improvement of turbine cycle characteristics.

[0007] Further, JP-A No. 2-211331 discloses the gas turbine which isprovided with an intermediate cooler which is provided between the twotypes of compressors of high pressure and low pressure, and whereinmeans for detecting a temperature and a humidity at the inlet of thehigh pressure compressor are provided, and a feed water flow to theintermediate cooler is controlled. However, this control does not teachnor suggest water injection into the compressor itself, and is notconcerned with control of humidity at the inlet of the compressor.

[0008] In consideration of an actual operation of a gas turbine or acombined cycle using a gas turbine and a steam turbine, there isrequired a development of a system which can realize a safety operationof the gas turbine while always ensuring protection of the gas turbineitself, and which can improve its output and thermal efficiency using asimple arrangement.

SUMMARY OF THE INVENTION

[0009] An object of the invention is to provide a gas turbine which canrealize improvements both on its output and thermal efficiency throughinjection of liquid droplets into intake air introduced to the inlet ofthe compressor using simple facilities suitable for actual application,and also a safety operating system using the same.

[0010] A first present invention is a gas turbine having a compressorfor compressing an air supplied therein and discharging a compressedair, a combustor for combusting the compressed gas from the compressorand a fuel and a gas turbine to be driven by a combustion gas from thecombustor, characterized by comprising an injection unit, arranged at anupstream side of the compressor and constructed so that water dropletsare sprayed into the air to be supplied to the compressor to lower thetemperature of the air to be supplied into the compressor than anatmospheric temperature and the sprayed water droplets introduced intothe compressor with the air having lowered in temperature are evaporatedduring passage through the compressor, a detection unit for detectingthe humidity of air to be supplied to the compressor, and a controllingunit for controlling a quantity of water droplets to be sprayed from theinjection unit on the basis of a signal from the detection unit.

[0011] For example, it is possible to control a spray quantity of theliquid droplets according to the detected signal.

[0012] The humidity of intake air at the upstream side of the injectionunit, for example, is detected and a spray quantity of the liquiddroplets is controlled to be more when the humidity is low than when itis high.

[0013] Further, it is preferable for the control unit to have adetection unit for detecting the temperature and humidity of airsupplied to the compressor and control a spray quantity of waterdroplets sprayed from the injection unit on the basis of the detectionsignal. By detecting the temperature of air at the upstream side of theinjection unit, the spray quantity of water droplets is controlled to bemore at a lower temperature than at a higher temperature, and the sprayquantity of water droplets is controlled to be more when the humidity ofair at the upstream side of the injection unit is lower than when thehumidity is higher than when low.

[0014] Further, it is possible to control the above-mentioned sprayquantity on the basis of output, etc. and use it as a limit value of thespray quantity on the basis of the above-mentioned detection signal. Thecontrol unit has a limit value set for a spray quantity of waterdroplets from the injection unit on the basis of the detection signaland controls the spray quantity to be within the above-mentioned limitvalue.

[0015] For example, a spray quantity of water droplets is determinedaccording to output, for example. In this case, the temperature ofintake air at the upstream side of the injection unit is detected, theabove-mentioned limit value is made higher when the temperature is lowerthan when high, the above-mentioned limit value is made higher when thehumidity of intake air at the upstream of the injection unit is lowerthan when high, and a spray quantity of the water droplets is controlled(corrected) not to exceed the limit value.

[0016] Thereby, the soundness of the compressor is secured and a highoutput operation of the gas turbine can be executed. Since a water sprayquantity is adjusted by considering the humidity of intake air whenwater droplets are injected into the intake air, a quantity of waterdroplets introduced into the compressor without evaporating until theinjected water droplets reach the compressor inlet can be controlled tobe a proper quantity, and a quantity of water droplets having beenevaporated until they reach the compressor inlet and a quantity of waterdroplets having been evaporated within the compressor can be suitablycontrolled. Therefore, the gas turbine can be operated at a high outputwhile securing the soundness of the plant, taking into consideration aninfluence on the compressor.

[0017] Thereby, it is possible to practice water injection whilesecuring a safety operation of the gas turbine main body.

[0018] For example, when detecting means for detecting the temperatureand humidity of gas at the upstream side of the compressor is provided,a water spray quantity limit value related to the temperature andhumidity is set and the water quantity is controlled so that a realeffective water spray quantity does not exceed the above-mentioned waterspray quantity limit value during a water spraying operation, such casescan be considered that the effective water spray quantity is calculatedfrom the humidity of gas at the compressor discharge portion and thehumidity of gas at the upstream side of the injection unit and that itis calculated from a water quantity indication value of the water supplysystem and a drain occurrence amount in the intake air duct of theupstream side of the compressor. However, any case can be taken. Thehumidity of compressor discharge air can be measured by continuouslydrafting air into a tank for sampling which is provided with a humiditydetecting means.

[0019] A second invention is a gas turbine, having a compressor forcompressing an air supplied therein and discharging a compressed air, acombustor for combusting the compressed gas from the compressor and afuel and a gas turbine to be driven by a combustion gas from thecombustor, and characterized by comprising an injection unit, arrangedat an upstream side of the compressor and constructed so that waterdroplets are sprayed into the air to be supplied to the compressor tolower the temperature of the air to be supplied into the compressor thanan atmospheric temperature and the sprayed water droplets introducedinto the compressor with the air having lowered in temperature areevaporated during passage through the compressor, a detection unit fordetecting the opening of a compressor inlet vane, arranged in thecompressor, and a controlling unit for controlling a quantity of waterdroplets to be sprayed from the injection unit on the basis of a signalfrom the detection unit.

[0020] For example, it is possible to set a limit value of a quantity ofwater droplets sprayed from the injection unit on the basis of theabove-mentioned detection signal and control the spray quantity to bewithin the limit value. It is possible to set the above-mentioned limitvalue to be larger when the above-mentioned compressor vane opening islarger than when small. Since a quantity of air decreases according to achange in the guide vane angle or opening, a quantity of water isdecreased as well.

[0021] Thereby, it is possible to inject a quantity of watercorresponding to a quantity of air at the compressor inlet at the timeof partial load operation. Further, it is possible to secure thesoundness of the apparatus and devices of the plant at the time ofpartial load operation.

[0022] There are cases such that a quantity of air introduced into thecompressor is decreased by throttling the guide vane of the compressorand that the quantity of air decreases because of rising in atmospherictemperature, however according to the present construction, it ispossible to inject a suitable quantity of water according to an increaseor decrease in an intake air quantity at the time of a partial loadoperation. It is possible to suppress a condition such as an excessiveamount of water spray, and operate the gas turbine at a high outputwhile protecting the apparatus and devices.

[0023] Further, it is preferable to detect the above-mentionedcompressor inlet guide vane angle and the compressor inlet air quantityand limit the spray quantity of water droplets according to the intakeair quantity. In this case, it is further preferable to have determinedthe water droplet spray quantity according to ratios thereof to thecompressor inlet air quantity because it is possible to influence, onthe water droplet spray quantity, difference between individual machinesof the same kind, a decrease in a compressor intake air quantity due toaged deterioration and a scale ratio in machine kinds of similarfigures.

[0024] A third invention is a gas turbine having a compressor forcompressing an air supplied therein and discharging a compressed air, acombustor for combusting the compressed gas from the compressor and afuel and a gas turbine to be driven by a combustion gas from thecombustor, characterized by comprising an injection unit, arranged at anupstream side of the compressor and constructed so that water dropletsare sprayed into the air to be supplied to the compressor to lower thetemperature of the air to be supplied into the compressor than anatmospheric temperature and the sprayed water droplets introduced intothe compressor with the air having lowered in temperature are evaporatedduring passage through the compressor, and a controlling unit forcontrolling the injection unit so as to stop injection of water dropletsfrom the injection unit at time of starting of the gas turbine and startinjection of water droplets from the injection unit after the gasturbine has come into a rated operation.

[0025] A shift of an operation of the gas turbine to a rated operationcan be detected by a prescribed opening of the compressor inlet guidevane (an opening at time of normal operation, a full opening, etc.).Further, it can be detected by coming into an operation of a constantcombustion temperature.

[0026] After the shift to the rated operation, for example, when adifference occurs between a required output value and a real outputvalue, it is possible to operate by controlling the above-mentionedwater droplet spray quantity so that the real output becomes a requiredoutput.

[0027] Thereby, it is possible to provide a gas turbine with a safeoutput increasing mechanism by water spray while protecting the gasturbine.

[0028] Even under the condition the gas turbine is operated at aconstant partial load, it is possible to control so as to execute awater spray operation. Thereby, the thermal efficiency at the time of apartial load operation can be improved.

[0029] A fourth invention is a gas turbine having a compressor forcompressing an air supplied therein and discharging a compressed air, acombustor for combusting the compressed gas from the compressor and afuel and a gas turbine to be driven by a combustion gas from thecombustor, characterized by comprising an injection unit, arranged at anupstream side of the compressor and constructed so that water dropletsare sprayed into the air to be supplied to the compressor to lower thetemperature of the air to be supplied into the compressor than anatmospheric temperature and the sprayed water droplets introduced intosaid compressor with the air having lowered in temperature areevaporated during passage through the compressor, the injection unithaving a plurality of spray nozzles for spraying water droplets, and acontrolling unit for controlling the injection unit so that the numberof the spraying nozzles spraying water droplets more than a prescribedquantity of water droplets becomes more than the number of the sprayingnozzles spraying water droplets less than the prescribed quantity ofwater droplets.

[0030] For example, the above-mentioned injection unit has a watersupply apparatus, a water supply main pipe line for supplying water fromthe water supply apparatus, a water supply header distributing watersupplied from the water supply main pipe to a plurality of water supplypipes, and nozzles arranged on water supply pipes in which waterdistributed by the header flows for spraying the water droplets, and itcan be further provided with a control unit which control so that thenumber of water supply pipes for supplying the water when the waterdroplet spray quantity is larger than a prescribed amount becomes morethan the number of water supply pipes supplying the water when the waterdroplet spray quantity is smaller than the prescribed quantity.

[0031] Further, in the case where the above-mentioned spray nozzle is atwo-fluid nozzle, the spray nozzle can be arranged so as to communicatewith an air supply main pipe supplying air from the air supplyapparatus, an air supply header distributing the air supplied from theair supply main pipe and air supply pipes in which air distributed bythe header flows.

[0032] Further, for example, the construction of the above-mentionedwater supply header of the injection unit can be constructed as follows:

[0033] The injection unit comprises a water supply apparatus, a watersupply main pipe supplying water from the water supply apparatus, a mainwater supply header distributing water supplied from the water supplymain pipe to a plurality of water supply branch pipes, an auxiliarywater supply header distributing water flowing the water supply branchpipes to a plurality of water supply pipes, and nozzles, arranged on thewater supply pipes in which water branched by the auxiliary water supplyheader flows, for spraying water droplets.

[0034] Thereby, even when the spray quantity of water droplets increasesand decreases, it is possible to stably spray water droplets and anoperation of high output can be carried out with the stable water spray.

[0035] Further, it is possible to suppress non-uniformity in the waterquantity supplied to the spray nozzles, etc.

[0036] A fourth invention is characterized by providing a water supplyflow regulation valve on an upstream side of the water supply header orwater supply main header and controlling a water spray quantity by thewater supply flow regulation valve. Thereby, water can be suppliedsimultaneously to the water spray nozzles at a fixed flow rate.

[0037] Further, with respect to a control of a flow rate, it is possibleto provide a feed water flow regulation valve each between a downstreamside of the feed water main header and the upstream side of the feedwater auxiliary headers, and control a water spray quantity by the feedwater flow regulation valve according to a required water sprayquantity. It also is possible to control the water spray quantity bychanging the number of the operating feed water auxiliary headersaccording to the water spray quantity. Further, it is possible toprovide a feed water regulation valve between a downstream side of thefeed water main header or feed water auxiliary header and an upstreamside of the spray water piping and control a water spray quantitythereby. Further, it is possible to provide a feed water flow regulationvalve between a downstream side of the spray water piping and anupstream side of the spray nozzles and control the water spray quantityfrom the spray nozzles thereby.

[0038] A fifth invention is a gas turbine having a compressor forcompressing an air supplied therein and discharging a compressed air, acombustor for combusting the compressed gas from the compressor and afuel and a gas turbine to be driven by a combustion gas from thecombustor, characterized by comprising an injection unit, arranged at anupstream side of the compressor and constructed so that water dropletsare sprayed into the air to be supplied to the compressor to lower thetemperature of the air to be supplied into the compressor than anatmospheric temperature and the sprayed water droplets introduced intothe compressor with the air having lowered in temperature are evaporatedduring passage through the compressor, the infection unit having a watersupply system, an air supply system and a spray nozzle for beingsupplied with water and air from the water supply system and air supplysystem and spraying water droplets, and a controlling unit forcontrolling the water supply quantity and air supply quantity so as tosuppress variation between a ratio of water and air supplied to thespray nozzle when the water droplet supply quantity is small and a ratioof water and air supplied to the spray nozzle when the water dropletsupply quantity is large.

[0039] In this manner, an air supply quantity is controlled according toa change in a water supply quantity so that a ratio of air and waterbecomes constant (so that variation in the ratio is suppressed)according to a water spray quantity.

[0040] Thereby, it is possible to obtain water droplets of prescribeddiameter while keeping the air quantity small (it is preferable in acase where a water quantity is relatively small). In a case where air istaken from the compressor, it is possible to supply a larger amount ofair from the taken air to the combustor, and an operation of high outputor high efficiency can be carried out even if the water droplet sprayquantity is changed.

[0041] A sixth invention is a gas turbine, having a compressor forcompressing an air supplied therein and discharging a compressed air, acombustor for combusting the compressed gas from the compressor and afuel and a gas turbine to be driven by a combustion gas from thecombustor, and characterized by comprising an injection unit, arrangedat an upstream side of the compressor and constructed so that waterdroplets are sprayed into the air to be supplied to the compressor tolower the temperature of the air to be supplied into the compressor thanan atmospheric temperature and the sprayed water droplets introducedinto the compressor with the air having lowered in temperature areevaporated during passage through the compressor, the injection unithaving a water supply system, an air supply system and a spray nozzlefor being supplied with water from the water supply system and sprayingwater droplets and spraying water droplets, and a controlling unit forcontrolling the water supply quantity and air supply quantity as toincrease a ratio of water to air, supplied to the spray nozzle when aspray quantity of water droplets is more, as compared with a small sprayquantity.

[0042] Thereby, it is possible to obtain water droplets of a prescribeddiameter while keeping the air quantity small (it is preferable when thewater quantity is relatively small). In a case where air is taken fromthe compressor, it is possible to supply a larger amount of air from thetaken air to the combustor, and an operation of high output or highefficiency can be carried out even if the water droplet spray quantitychanges.

[0043] A seventh invention is a gas turbine, having a compressor forcompressing an air supplied therein and discharging a compressed air, acombustor for combusting the compressed gas from the compressor and afuel and a gas turbine to be driven by a combustion gas from thecombustor, and characterized by comprising an injection unit, arrangedat an upstream side of the compressor and constructed so that waterdroplets are sprayed into the air to be supplied to the compressor tolower the temperature of the air to be supplied into the compressor thanan atmospheric temperature and the sprayed water droplets introducedinto the compressor with the air having lowered in temperature areevaporated during passage through the compressor, said injection unithaving a water supply system, an air supply system and a spray nozzlefor being supplied with water and air from the water supply system andair supply system and spraying water droplets, and a controlling unitfor controlling the water supply quantity and air supply quantity so asto increase and decrease the water supply quantity according to anincrease and a decrease of a spray quantity of water droplets andmaintain the air supply quantity to be constant.

[0044] Thereby, it is possible to execute a high output operation bywater spray while keeping the soundness of the apparatus and devices,with a simple control.

[0045] An eighth invention is a gas turbine, having a compressor forcompressing an air supplied therein and discharging a compressed air, acombustor for combusting the compressed gas from the compressor and afuel and a gas turbine to be driven by a combustion gas from thecombustor, and characterized by comprising an injection unit, arrangedat an upstream side of the compressor and constructed so that waterdroplets are sprayed into the air to be supplied to the compressor tolower the temperature of the air to be supplied into the compressor thanan atmospheric temperature and the sprayed water droplets introducedinto the compressor with the air having lowered in temperature areevaporated during passage through the compressor, the injection unithaving a water supply system, an air supply system and a spray nozzlefor being supplied with water and air from the water supply system andair supply system and spraying water droplets, and a controlling unitfor controlling the injection unit so as to start supplying of air tothe spray nozzle first and then start to supplying of water to the aspray nozzle, thereby to start spraying of water droplets.

[0046] A ninth invention is a gas turbine, having a compressor forcompressing an air supplied therein and discharging a compressed air, acombustor for combusting the compressed gas from the compressor and afuel and a gas turbine to be driven by a combustion gas from thecombustor, and characterized by comprising an injection unit, arrangedat an upstream side of the compressor and constructed so that waterdroplets are sprayed into the air to be supplied to the compressor tolower the temperature of the air to be supplied into the compressor thanan atmospheric temperature and the sprayed water droplets introducedinto the compressor with the air having lowered in temperature areevaporated during passage through the compressor, the injection unithaving a water supply system, an air supply system and a spray nozzlefor being supplied with water and air from the water supply system andair supply system and spraying water droplets, and a controlling unitfor controlling the injection unit so that the water droplet spraying isstopped by decreasing a quantity of air supplied to the spray nozzlefirst and then decreasing a quantity of water supplied to the spraynozzle.

[0047] Thereby, it is possible to secure the soundness of the apparatusand devices at a time of starting the water spray operation or at a timeof stopping the water spray operation, and it is possible to provide agas turbine which outputs a high output by the water spray operation.Further, it is possible to suppress occurrence of water droplets havingan undesired diameter at the time of starting and stopping.

[0048] A tenth invention is a gas turbine having a compressor forcompressing an air supplied therein and discharging a compressed air, acombustor for combusting the compressed gas from the compressor and afuel and a gas turbine to be driven by a combustion gas from thecombustor, and characterized by comprising an injection unit, arrangedat an upstream side of the compressor and constructed so that waterdroplets are sprayed into the air to be supplied to the compressor tolower the temperature of the air to be supplied into the compressor thanan atmospheric temperature and the sprayed water droplets introducedinto the compressor with the air having lowered in temperature areevaporated during passage through the compressor, and a controlling unitfor controlling the injection unit so as to first issue a signal forstopping the water droplet spraying and then issue an instruction todecrease the compressor inlet guide vane opening on the basis of a gasturbine trip signal, during operation of the injection unit.

[0049] Thereby, a high output can be obtained by the water sprayoperation, and even if a gas turbine trip occurs during the water sprayoperation, it is possible to provide a gas turbine of a high safetywhich can effect a smooth trip, securing the soundness of the apparatusand devices.

[0050] An eleventh invention is a gas turbine having a compressor forcompressing an air supplied therein and discharging a compressed air, acombustor for combusting the compressed gas from the compressor and afuel and a gas turbine to be driven by a combustion gas from thecombustor, characterized by comprising an injection unit, arrangedwithin an intake air duct at an upstream side of the compressor andconstructed so that water droplets are sprayed into the air to besupplied to the compressor to lower the temperature of the air to besupplied into the compressor than an atmospheric temperature and thesprayed water droplets introduced into the compressor with the airhaving lowered in temperature are evaporated during passage through thecompressor, and a controlling unit, having a plurality of airtemperature detectors arranged in the duct in a peripheral direction,for controlling the injection unit so as to decrease a quantity of waterspray when a deviation in detected value reaches to a prescribed value,during an operation of spraying water droplets.

[0051] Further, it is possible to control the water spray quantity so asto decrease when the a set temperature set by taking account of icingand so on exceeds a prescribed value. When the water spray quantity isdecreased, it is possible to control so as to increase, according to adetection value, a flow rate of water flowing in a spray nozzle portioncorresponding to a position in which a detection value changes largelyby a prescribed value form an average value of the other detectionvalues, or it is possible to decrease the water spray quantity of thewhole spray nozzles.

[0052] A twelfth invention is a gas turbine having a compressor forcompressing an air supplied therein and discharging a compressed air, acombustor for combusting the compressed gas from the compressor and afuel and a gas turbine to be driven by a combustion gas from thecombustor, characterized by comprising an injection unit, arrangedwithin an intake air duct at an upstream side of the compressor andconstructed so that water droplets are sprayed into the air to besupplied to the compressor to lower the temperature of the air to besupplied into the compressor than an atmospheric temperature and thesprayed water droplets introduced into the compressor with the airhaving lowered in temperature are evaporated during passage through thecompressor, and a controlling unit for controlling the injection unit soas to monitor a flow rate by weight of air introduced into thecompressor and decrease a quantity of water spray when the flow ratereaches to a prescribed value, during operation of spraying waterdroplets.

[0053] Thereby, since the change can be directly monitored, stall andicing can be precisely suppressed, whereby a gas turbine which can carryout a high output operation by water spray can be provided while keepingthe soundness of the apparatus and devices.

[0054] In a case where a device for measuring an air quantity at thecompressor inlet is provided and a water quantity is controlled relativeto the air quantity at the compressor inlet during the water sprayoperation, any of the operations can be effected in one of which onearbitrary constant value is set in advance as an allowable variationrange and the water quantity is decrease not to exceed the allowablevariation range, in the other of which water supply is stopped when thewater quantity exceeds the allowable variation range. In a case ofstopping of water supply, any methods can be taken one of which is amethod of stopping water supply by an operation of the feed waterstopping valve of the water supply system when it exceeds the allowablevariation range and other is a method of stopping the water supply bystoping the feed water pump of the water supply system.

[0055] Further, this control unit is preferable to be applied in thecase where such a water spray quantity is injected that some of thequantity thereof has not been evaporated and remains as water dropletsin the intake duct and the quantity of the not-evaporated liquiddroplets are introduced into the compressor.

[0056] For example, the above-mentioned detection is executed at aninterval of several minutes (for example, 2 to 3 minutes), and it ispossible to judge after monitoring at the detection interval.

[0057] Since an air quantity decreases as the atmospheric temperaturerises, in order to distinguish it from an decrease of the air quantitydue to stall, it is preferable to calculate an air quantity change bydetecting the air temperature.

[0058] Further, the air temperature is preferable to be detected at acompressor inlet portion (for example, between a downstream side of theinjection unit and the compressor inlet).

[0059] It is possible to replace the detection of an inlet air flow rateby detection of a compressor discharge pressure by providing a detectiondevice detecting a compressor discharge pressure on a compressordischarge air flow passage.

[0060] Alternatively, it is possible to provide means for detecting agas turbine intake air temperature and a control unit controlling so asto inject water spray when the air temperature becomes a constant valueor more. At this time, although a gas temperature at an upstream side ofthe injection unit and a gas temperature at a downstream side of theinjection unit are considered as a gas temperature to be detected forthe control, any gas temperature can be used. In a case where it isdetected at the downstream side of the injection unit, it is possible todetect the air temperature at a plurality of points in the same plane ina flow direction. When the air temperature lowers than a lower limitvalue, a water spray injection quantity is limited according to the airtemperature. Otherwise, it is possible to stop the water supply.

[0061] Thereby, a stable operation of the gas turbine can be achievedwhile avoiding an icing phenomenon on the compressor inlet guide vanes.

[0062] Further, by providing means for detecting the temperature andhumidity of a gas turbine intake air and a calculator for calculating awet-bulb potential temperature from the humidity, or providing means fordetecting an air wet-bulb potential temperature, it is possible toprovide a control unit controlling so as to inject water spray when thewet-bulb potential temperature is a constant value or more. In thiscase, although a wet-bulb potential temperature at a upstream side ofthe injection unit and a wet-bulb potential temperature at a downstreamside of the injection unit are considered as a wet-bulb potentialtemperature used for the control, any of which can be used. In a casewhere the wet-bulb potential temperature lowers than a lower limitvalue, the water spray injection quantity can be limited according tothe temperature or it is possible to stop the water supply.

[0063] Thereby, a stable operation of the gas turbine can be achievedwhile avoiding an icing phenomenon on the compressor inlet guide vanes.

[0064] A thirteenth invention is a gas turbine having a compressor forcompressing an air supplied therein and discharging a compressed air, acombustor for combusting the compressed gas from the compressor and afuel and a gas turbine to be driven by a combustion gas from thecombustor, characterized by comprising an injection unit, arrangedwithin an intake air duct at an upstream side of the compressor andconstructed so that water droplets are sprayed into the air to besupplied to the compressor to lower the temperature of the air to besupplied into the compressor than an atmospheric temperature and thesprayed water droplets introduced into the compressor with the airhaving lowered in temperature are evaporated during passage through thecompressor, a detection unit for detecting the pressure of a casing wallof an inlet guide vane portion of the compressor, and a controlling unitfor controlling a quantity of water spray on the basis of the detectedwall pressure, during an operation of water droplet injection.

[0065] For example, the above-mentioned control unit monitors the casingwall pressure at a compressor inlet guide vane inlet and controls so asto decrease the water spray quantity when the flow rate becomes aprescribed value or more, during the water spray operation.

[0066] Thereby, it is possible to monitor the casing pressure of thecompressor inlet guide vane inlet and approximate an air flow ratechange thereby, whereby it is possible to easily detect a conditionchange, and make the output high by the water spray injection whileeasily securing the soundness of the apparatus and devices.

[0067] Further, other than it, it is possible to detect the pressureinside the compressor and control so as to decrease the water injectionquantity on the basis of rising in the pressure more than a prescribedvalue. Thereby, the detecting device is easily installed and the airquantity can be easily detected.

[0068] Further, it is possible to detect a change in pressure inside thecompressor and to control so as to decrease the water spray quantitywhen the pressure change becomes larger than a prescribed value.Whereby, it is possible to directly measure an abnormal condition anddetect precisely the event.

[0069] A fourteenth invention is a gas turbine having a compressor forcompressing an air supplied therein and discharging a compressed air, acombustor for combusting the compressed gas from the compressor and afuel and a gas turbine to be driven by a combustion gas from thecombustor, characterized by comprising an injection unit, arrangedwithin an intake air duct at an upstream side of the compressor andconstructed so that water droplets are sprayed into the air to besupplied to the compressor to lower the temperature of the air to besupplied into the compressor than an atmospheric temperature and thesprayed water droplets introduced into the compressor with the airhaving lowered in temperature are evaporated during passage through thecompressor, and a controlling unit for controlling the injection unit soas to monitor a discharge pressure of the compressor and decrease aquantity of water spray when the discharge pressure becomes less aprescribed value, during operation of spraying water droplets.

[0070] For example, the above-mentioned control unit monitors acompressor discharge pressure and control so as to the water sprayquantity when the discharge pressure becomes less than a prescribedvalue, during a water spray injection operation. Thereby, it is possibleto rapidly detect an abnormal condition which is high in pressure level,such as icing, stall, etc. Therefore, it is possible to effect a highoutput operation by the water spray injection and detect earlyoccurrence of icing, stall, etc. and maintain the soundness of theapparatus and devices.

[0071] When a means for detecting a compressor discharge pressure isprovided and a water injection quantity is controlled according to thecompressor discharge pressure during the water spray injectionoperation, a constant value is set in advance as an allowable variationrange and it is possible to operate so as to decrease not to exceed theallowable variation range or to operate so as to stop the water supplywhen it exceed the allowable variation range.

[0072] A fifteenth invention is a gas turbine having a compressor forcompressing an air supplied therein and discharging a compressed air, acombustor for combusting the compressed gas from the compressor and afuel and a gas turbine to be driven by a combustion gas from thecombustor, characterized by comprising an injection unit, arrangedwithin an intake air duct at an upstream side of the compressor andconstructed so that water droplets are sprayed into the air to besupplied to the compressor to lower the temperature of the air to besupplied into the compressor than an atmospheric temperature and thesprayed water droplets introduced into the compressor with the airhaving lowered in temperature are evaporated during passage through thecompressor, and a controlling unit for monitoring an adiabaticefficiency of the compressor and controlling a quantity of water sprayon the basis of the adiabatic efficiency, during operation of waterdroplet injection.

[0073] For example, the above-mentioned control unit monitors acompressor adiabatic efficiency and controls so as to decrease the waterspray quantity when the adiabatic efficiency lowers less than aprescribed value, during the water spray injection operation.

[0074] Thereby, even if an atmospheric temperature changes, thetemperature can be detected, and an icing, stall, etc. can be detected.Therefore, even if the atmospheric temperature changes, it is possibleto easily protect the apparatus and devices from the icing, stall, etc.and to provide a gas turbine of high output by the water sprayinjection. Further, mismatching between stages inside the compressor canbe detected, a further safe operation can be effected.

[0075] When a means for measuring a compressor adiabatic efficiency isprovided and a water quantity is controlled according to the compressoradiabatic efficiency during the water spray injection operation, aconstant value is set in advance as an allowable variation range, andany of an operation in which the water quantity is decreased not toexceed the allowable variation range and an operation in which the watersupply is stopped when it exceeds the allowable variation range can bepracticed.

[0076] A sixteenth invention is a gas turbine having a compressor forcompressing an air supplied therein and discharging a compressed air, acombustor for combusting the compressed gas from the compressor and afuel and a gas turbine to be driven by a combustion gas from thecombustor, characterized by comprising an injection unit, arrangedwithin an intake air duct at an upstream side of the compressor andconstructed so that water droplets are sprayed into the air to besupplied to the compressor to lower the temperature of the air to besupplied into the compressor than an atmospheric temperature and thesprayed water droplets introduced into the compressor with the airhaving lowered in temperature are evaporated during passage through saidcompressor, and a controlling unit for monitoring an exhaust gastemperature and controlling a quantity of water spray on the basis ofthe exhaust gas temperature, during an operation of water dropletinjection.

[0077] For example, the above-mentioned control unit monitors an exhaustgas temperature and control so as to decrease the spray water quantitywhen the exhaust gas temperature becomes a prescribed value or more,during the water spray injection operation.

[0078] Thereby, it is possible to rapidly detect a change in event andsuitably protect the apparatus and devices from an abnormal condition,and achieve a high output operation of the gas turbine by the waterspray injection.

[0079] By providing a means for detecting a combustion exhaust gastemperature, when the water quantity is controlled according to thecombustion exhaust gas temperature during the water spray injectionoperation, a constant value is set in advance as an allowable variationrange and any of an operation in which the water quantity is decreasednot to exceed the allowable variation range and an operation in whichthe water supply is stopped when it exceeds the allowable variationrange, can be effected.

[0080] A seventeenth invention is a gas turbine having a compressor forcompressing an air supplied therein and discharging a compressed air, acombustor for combusting the compressed gas from the compressor and afuel and a gas turbine to be driven by a combustion gas from thecombustor, characterized by comprising an injection unit, arrangedwithin an intake air duct at an upstream side of the compressor andconstructed so that water droplets are sprayed into the air to besupplied to the compressor to lower the temperature of the air to besupplied into the compressor than an atmospheric temperature and thesprayed water droplets introduced into the compressor with the airhaving lowered in temperature are evaporated during passage through thecompressor, and a controlling unit for monitoring vibrations of a gasturbine bearing and controlling a quantity of water spray on the basisof the vibration value, during an operation of water droplet injection.

[0081] For example, the above-mentioned control unit monitors vibrationsof a gas turbine bearing and controls so as to decrease the water sprayquantity when the vibrations exceeds a prescribed value, during thewater spray injection operation.

[0082] Thereby, it can be directly detected that stool occurs partiallyin a peripheral direction, and partial stall and icing can be directlydetected. It is possible to protect the apparatus and devices fromabnormality by detection of partial stall and icing, and provide a highoutput operation of gas turbine by the water spray injection. Further,it is possible to detect suitably vibrations due to unbalance of a gasturbine rotating portion, caused by ununiformity in water dropletsintroduced in the compressor and carry out a high safety operation.

[0083] In a case where by providing a means for detecting vibrations ofthe gas turbine bearing, and the water injection quantity is controlledaccording to the vibrations of the bearing during the water sprayinjection operation, a constant value is set in advance as an allowablevariation range, it is possible to effect an operation that the waterquantity is decreased not to exceed the allowable variation range or anoperation that the water supply is stopped when it exceeds the allowablevariation range.

[0084] A eighteenth invention is a gas turbine having a compressor forcompressing an air supplied therein and discharging a compressed air, acombustor for combusting the compressed gas from the compressor and afuel and a gas turbine to be driven by a combustion gas from thecombustor, characterized by comprising an injection unit, arrangedwithin an intake air duct at an upstream side of the compressor andconstructed so that water droplets are sprayed into the air to besupplied to the compressor to lower the temperature of the air to besupplied into the compressor than an atmospheric temperature and thesprayed water droplets introduced into the compressor with the airhaving lowered in temperature are evaporated during passage through thecompressor, and a controlling unit for monitoring a thrust bearing metaltemperature of the gas turbine and controlling a quantity of water sprayinjection on the basis of the thrust bearing metal temperature, duringan operation of water droplet injection.

[0085] For example, the above-mentioned control unit monitors a metaltemperature of a gas turbine thrust bearing and controls so as todecrease the water spray quantity when the metal temperature exceeds aprescribed value, during the water spray injection operation.

[0086] Thereby, a temperature change in the thrust bearing can bedetected and if an unbalance in the thrust bearing occurs, it can besurely detected. It is possible to protect the apparatus and devicesfrom abnormality caused by the unbalance, and provide a high outputoperation of gas turbine by the water spray injection.

[0087] In a case where by providing a means for detecting a metaltemperature of the gas turbine thrust bearing, and the water quantity iscontrolled according to the metal temperature of the thrust bearingduring the water spray injection operation, a constant value is set inadvance as an allowable variation range, it is possible to effect anoperation that the water quantity is decreased not to exceed theallowable variation range or an operation that the water supply isstopped when it exceeds the allowable variation range.

[0088] A nineteenth invention is a gas turbine having a compressor forcompressing an air supplied therein and discharging a compressed air, acombustor for combusting the compressed gas from the compressor and afuel and a gas turbine to be driven by a combustion gas from thecombustor, characterized by comprising an injection unit; arrangedwithin an intake air duct at an upstream side of the compressor andconstructed so that water droplets are sprayed into the air to besupplied to the compressor to lower the temperature of the air to besupplied into the compressor than an atmospheric temperature and thesprayed water droplets introduced into the compressor with the airhaving lowered in temperature are evaporated during passage through thecompressor, and a controlling unit for monitoring an axial flow velocityof fluid flowing in the compressor and controlling a quantity of waterspray on the basis of the axial flow velocity, during an operation ofwater droplet injection.

[0089] For example, the above-mentioned control unit monitors an axialflow velocity of fluid inside the compressor and controls so as todecrease the water spray quantity when the axial flow velocity loweredto a prescribed value or less, during the water spray injectionoperation. Since it is determined irrespective of such conditions asatmospheric temperature, etc., the control can be easily carried out anda precise control can be effected with respect to this point. Further,it is possible to determine a limit value of a water spray quantity onthe basis of this value and make it a control ground, whereby directcontrol can be effected.

[0090] Thereby, it is possible to protect the apparatus and devices fromabnormality caused by an icing and so on and provide a high outputoperation of gas turbine by the water spray injection.

[0091] In a case where by providing a means for calculating an axialflow velocity inside the compressor, and the water quantity iscontrolled according to the axial flow velocity of fluid in thecompressor during the water spray injection operation, although theaxial flow velocity can be considered to be calculated at any stage, itis possible to calculate an axial flow velocity at the final stage ofthe compressor from an air quantity at the compressor inlet, acompressor discharge pressure and a compressor discharge temperature. Anoperation method in which a constant value is set in advance as anallowable variation range, and the water quantity is decreased not toexceed the allowable variation range and an operation that the watersupply injection is stopped when it exceeds the allowable variationrange are considered, however, any of the operations can be used.Further, When the water supply is stopped, although there are a methodof stopping water supply by an operation of feed water shut-off valve ofa feed water system and a method of stopping water supply by stopping afeed water pump, any of the methods can be used.

[0092] Alternatively, it is possible to provide a means for detecting adrain quantity in the compressor inlet air intake portion and a controlunit controlling the water quantity according to the drain quantity. Anoperation method in which an arbitrary constant value is set in advanceas an allowable variation range, and the water quantity is decreased notto exceed the allowable variation range and an operation method in whichthe water supply is stopped when it exceeds the allowable variationrange are considered, however, any of the operation methods can be used.The drain quantity can be detected by arranging a high level switch inthe drain tank.

[0093] When the water supply is stopped, although there are a method ofstopping water supply by an operation of feed water shut-off valve of afeed water system and a method and an operation method of stopping watersupply by stopping the feed water pump of the feed water system, any ofthe methods can be used.

[0094] Thereby, since the compressor is made not to suck water dropletsof large diameter, it is possible to carry out a stable operation of thecompressor and gas turbine and to avoid wear of the compressor blades.

[0095] A twentieth invention is a gas turbine having a compressor forcompressing an air supplied therein and discharging a compressed air, acombustor for combusting the compressed gas from the compressor and afuel and a gas turbine to be driven by a combustion gas from thecombustor, characterized by comprising an injection unit, arrangedwithin an intake air duct at an upstream side of the compressor andconstructed so that water droplets are sprayed into the air to besupplied to the compressor to lower the temperature of the air to besupplied into the compressor than an atmospheric temperature and thesprayed water droplets introduced into the compressor with the airhaving lowered in temperature are evaporated during passage through saidcompressor, and a controlling unit for controlling said injection unitso as to increase a quantity of fuel supplied to the combustor at timeof water droplet spraying, as compared with a quantity of fuel suppliedto the combustor at time of stopping of water droplet spraying.

[0096] Further, it is preferable to have a control unit controlling soas to increase a fuel supply quantity supplied to the combustor morethan before the water spray injection starting on the basis of the waterspray injection starting and decrease the fuel supply quantity less thanbefore the water spray injection stopping on the basis of the waterspray injection stopping.

[0097] Further, at the time of water spray injection also, it ispreferable to provide a control unit controlling so as to increase afuel injection amount to the combustor more when the water droplet sprayinjection quantity is more, than when the water spray injection quantityis small.

[0098] Further, it is preferable to control (correct or compensate) thefuel supply quantity according to the humidity.

[0099] In a case where a gas turbine exhaust gas temperature is used tocontrol a gas turbine inlet temperature constant, a method of correctinga value detected of the gas turbine exhaust gas temperature according tothe humidity quantity at the gas turbine inlet and a method ofcorrecting a predetermined exhaust gas temperature control lineaccording to the humidity quantity at the gas turbine inlet areconsidered.

[0100] Concretely, for example, it is possible to increase a fuelinjection amount by correcting the exhaust gas temperature control lineset based on water droplet spray not practiced toward a high temperatureside during the water spray injection operation.

[0101] Alternatively, it is possible to increase the fuel injectionamount by correcting a measure value of exhaust gas temperature.

[0102] In a case where detection of the humidity around the compressoris practiced at an upstream side of the compressor, a method ofcalculating it from the humidity of gas at the upstream side of theinjection unit, water spray injection quantity from the injection unitand a drain amount occurred in the intake air duct can be considered.The detection of humidity can be practiced at the compressor dischargeportion.

[0103] Thereby, an operation of the gas turbine that always keen thecombustion temperature constant without influence of the water sprayinjection is possible and it is possible to achieve an output improvingeffect by water spray injection to the maximum.

[0104] Thereby, the combustion temperature is suitably corrected (forexample, corrected to a higher temperature side) and a furtherimprovement on output can be achieved during the water spray injectionoperation.

[0105] A twenty-first invention is a gas turbine having a compressor forcompressing an air supplied therein and discharging a compressed air, acombustor for combusting the compressed gas from the compressor and afuel and a gas turbine to be driven by a combustion gas from thecombustor, characterized by comprising an injection unit, arrangedwithin an intake air duct at an upstream side of the compressor andconstructed so that water droplets are sprayed into the air to besupplied to the compressor to lower the temperature of the air to besupplied into the compressor than an atmospheric temperature and thesprayed water droplets introduced into the compressor with the airhaving lowered in temperature are evaporated during passage through thecompressor, an detection unit for detecting NOx concentration in theexhaust gas, and a controlling unit for controlling a quantity of waterspray on the basis of the detected NOx concentration.

[0106] As compared with NOx countermeasures by water or steam sprayinginto the combustor, a mixing condition of water and air is betterbecause a gas that air and water in the combustor are mixedhomogeneously flows in the combustor. Therefore, it is possible realizea low NOx emission while suppressing combustion vibrations and effectingstable combustion, with a simple apparatus.

[0107] Based on a value detected of NOx concentration of gas turbineexhaust gas, a water quantity is controlled according to differencebetween a target NOx concentration and the above-mentioned gas turbineexhaust gas NOx concentration value, whereby it is possible to decreasethe NOx concentration to the target value.

[0108] A twenty-second invention is a gas turbine having a compressorfor compressing an air supplied therein and discharging a compressedair, a combustor for combusting the compressed gas from the compressorand a fuel and a gas turbine to be driven by a combustion gas from thecombustor, characterized by comprising a premixer provided in thecombustor for burning premixed gas formed by premixing fuel and air, aninjection unit, arranged within an intake air duct at an upstream sideof the compressor and constructed so that water droplets are sprayedinto the air to be supplied to the compressor to lower the temperatureof the air to be supplied into the compressor than an atmospherictemperature and the sprayed water droplets introduced into thecompressor with the air having lowered in temperature are evaporatedduring passage through the compressor, and a controlling unit formonitoring an adiabatic efficiency of the compressor and controlling aquantity of water spray on the basis of the adiabatic efficiency, duringan operation of water droplet injection.

[0109] Further, it is preferable to control so that a ratio of fuel toair in a premixed gas becomes higher when the water spray quantity ismore.

[0110] A variation in water spray quantities changes greatly a conditionof fluid. However, it is possible to suppress the combustion conditionbecoming unstable during the water spray injection operation by theinvention. Therefore, it is possible to provide a gas turbine which hasa high stability of combustion and is able to carry out a high outputoperation by water spray injection.

[0111] Further, in stead of the above-mentioned control unit, it ispossible to provide a NOx concentration detection device for detecting aNOx concentration of the combustion exhaust gas, a pressure variationdetection device for detecting pressure variation inside the combustor,and a control unit controlling so as to increase the above-mentionedwater droplet spray quantity when the NOx concentration reaches to aprescribed value or more, and decrease the water droplet spray quantitywhen the pressure variation becomes a prescribed value or more.

[0112] Thereby, an operation that an output is made higher by the waterspray injection, an emitted NOx concentration is lower and a combustionstability is higher.

[0113] Further, by providing a means for detecting the NOx concentrationof gas turbine exhaust gas and the pressure variation in the combustor,it is possible to control the water spray quantity at the upstream sideof the compressor so as to suppress the gas turbine exhaust gas NOxconcentration and the pressure variation in the combustor withinallowable values.

[0114] Further, in a case where steam or water is injected into thecombustor, also, in the similar manner, it is possible to control thewater injection quantity at the upstream side of the compressor and thewater or steam injection quantity to the combustor so that the gasturbine exhaust gas NOx concentration and the combustor inside pressurevariation during an operation of the water spray injection at theupstream side of the compressor each become within an allowable value.Thereby, it is possible to achieve a stable operation of the combustor.

[0115] Further, by providing a means for monitoring the gas turbineexhaust gas NOx concentration and the combustor inside pressurevariation, it is possible to control a premixed combustion ratio so thatthe gas turbine exhaust gas NOx concentration and the combustor insidepressure variation each do not exceed a constant value set in advanceduring the water spray injection operation. Thereby, it is possible toachieve a stable operation of the combustor.

[0116] With respect to the gas turbine explained above, it is possibleto make higher output of gas turbines already made and installed inaddition to gas turbines newly installed. In this case, the already madegas turbines each are provided with the above-mentioned injection unit,any of the above-mentioned control units according to an object ordemand, related apparatus and devices if necessary, as a gas turbineoutput augmenting system.

[0117] In this manner, the above-mentioned operation of each of theinventions can be achieved by providing the above-mentioned injectionunit, control unit, or, further necessary related apparatus and deviceseven in already made gas turbines.

[0118] Further, if it is accepted that there may be some cases whereinthe above-mentioned operation and effect are not sufficiently presented,instead of the above-mentioned injection unit, arranged within an intakeair duct at an upstream side of the compressor and constructed so thatwater droplets are injected into the air to be supplied to thecompressor to lower the temperature of the air to be supplied into thecompressor than an atmospheric temperature and the sprayed waterdroplets introduced into the compressor with the air having lowered intemperature are evaporated during passage through the compressor, or inaddition to the above-mentioned injection unit, the above-mentionedcontrol unit can be employed for a system or apparatus provided with acooling device for cooling air supplied to the compressor to increaseoutput. The cooling device can be a device for effecting direct orindirect heat exchange with air supplied to the injection unit and thecompressor, using a cold heat source such as ice, liquid air, etc.

BRIEF DESCRIPTION OF THE DRAWING

[0119]FIG. 1 is a schematic block diagram of a gas turbine of anembodiment of the invention;

[0120]FIG. 2A is a diagram indicating gas turbine output characteristicsversus atmospheric temperatures;

[0121]FIG. 2B is a diagram indicating water injection quantities versusatmospheric temperatures;

[0122]FIG. 3 is a diagram indicating allowable water injectionquantities relative to atmospheric temperatures and angles of compressorinlet guide vanes (IGV);

[0123]FIG. 4 is a diagram indicating allowable water injectionquantities relative to atmospheric temperatures and relative humidities;

[0124]FIG. 5A is a diagram indicating a limit value for quantities ofwater droplets to be introduced into the compressor;

[0125]FIG. 5B is a diagram indicating operation status along a wet aircurve;

[0126]FIG. 6 is a schematic block diagram of a gas turbine of anotherembodiment of the invention;

[0127]FIG. 7 is a block diagram indicating the control contents of anembodiment of the invention;

[0128]FIG. 8 is a diagram indicating relationship of water injectionquantities with particle diameter and air quantities when a air waterratio is constant;

[0129]FIG. 9 is a schematic block diagram of a gas turbine of anotherembodiment of the invention;

[0130]FIG. 10 is a diagram indicating relationships of water sprayquantities with auxiliary header water supply quantities;

[0131]FIG. 11A is a diagram indicating relationships of water sprayquantities with air water ratios and air quantities when the particlediameter is constant;

[0132]FIG. 11B is a diagram indicating relationships of water sprayquantities with particle diameter and air water ratios when air quantityis constant;

[0133]FIG. 12A is a schematic block diagram of a gas turbine of anotherembodiment of the invention;

[0134]FIG. 12B is a section taken along a line B-B of FIG. 12A;

[0135]FIG. 13 is a diagram indicating water injection limits relative tocompressor inlet temperatures when atmospheric temperature is low;

[0136]FIG. 14 is a schematic block diagram of a gas turbine of anotherembodiment of the invention;

[0137]FIG. 15 is a diagram indicating operational status of the gasturbine under occurrence of icing phenomena in the inlet of thecompressor;

[0138]FIG. 16 is a diagram indicating operational status of the gasturbine under occurrence of stall phenomena within the compressor;

[0139]FIG. 17A is a diagram indicating a change in velocity triangles ofa compressor rotor blade due to injection of water droplets into thecompressor;

[0140]FIG. 17B is a diagram indicating a change in incident angles ofthe compressor rotor blade with respect to a quantity of water dropletsto be injected into the compressor;

[0141]FIG. 18 is a block diagram indicating a method for calculating anaxial velocity at the final stage of the compressor for the purpose ofwater quantity limitation;

[0142]FIG. 19 is a schematic control block diagram indicating a controlcontrolling fuel injection quantities into a combustor;

[0143]FIG. 20 is a schematic control block diagram indicating a controlcontrolling fuel injection quantities into a combustor;

[0144]FIG. 21A is a diagrams indicating relationships of gas turbineexhaust gas NOx concentrations and water injection quantities in thecompressor inlet;

[0145]FIG. 21B is a diagrams indicating relationships of combustionvibrations and water injection quantities in the compressor inlet;

[0146]FIG. 22A is a diagrams indicating a relationship of gas turbineexhaust gas NOx concentrations and premixture combustion ratios in thecombustor; and

[0147]FIG. 22A is a diagrams indicating a relationship of combustionvibrations and premixture combustion ratios in the combustor.

DESCRIPTION OF EMBODIMENTS OF THE INVENTION

[0148] A first embodiment of the invention will be described withreference to FIGS. 1 and 2.

[0149] A gas turbine according to this embodiment of the invention asindicated in FIG. 1 comprises a compressor 1 which compresses anddischarges a gas, a combustor 2 to which the gas compressed by thecompressor is supplied, a turbine 3 which is driven by a combustion gasof the combustor 2, and a generator 4 which is connected to the shaft ofthe turbine 3. A gas turbine exhaust gas is introduced into an exhaustheat recovery boiler 72 for heat exchange with a steam or water whichbecomes a working medium to drive a steam turbine 73, then it isdischarged to the atmosphere. The steam turbine 73 which is driven bythe steam which is heated through the heat exchange with the gas turbineexhaust gas is directly coupled with the generator 4. A steam dischargedfrom the steam turbine 73 is cooled by a condenser 74 to be condensedinto water. An air suction chamber 11 takes in air to be supplied to thecompressor 1. Further, a louver 10 is normally provided in the upstreamside of the suction chamber 11. The louver 10 is provided with an airfilter which is installed on the side of the compressor (in thedownstream side). Since the air filter is provided immediatelydownstream of louver 10, its illustration is omitted. An intake duct 13is connected to the suction chamber 11 at the downstream side thereof,and a silencer 12 is installed within the intake duct. Further, withinthe intake duct 13, spray water piping 15, atomizing air piping 16 and aspray nozzle or nozzles 17 are provided in the downstream side of thesilencer 12. The intake duct 13 is connected to a compressor intakeportion 14 for introducing air into the compressor 1. Further, the spraywater piping 15 and the atomizing air piping 16 are arranged as aplurality of systems. In FIG. 1, a single system is illustrated.

[0150] Spray water is supplied from a feed water tank 18 to a feed waterheader 25 via a foreign matter removal strainer 19, a feed water pump20, a feed water shut-off valve 21, a feed water supply regulating valve22, a water flowmeter 23, and a foreign matter removal filter 24. Wateris supplied from the feed water header 25 to the spray water piping 15via a feed water header outlet flow regulating valve 26.

[0151] In a case where two-fluid spray nozzles are used, a water dropletatomizing air system becomes necessary. As a water droplet atomizingair, an air extracted from the compressor is supplied to a spray airheader 32 via an air shut-off valve 27, an air pressure regulating valve28, a foreign matter removing cyclone separator 29, an air flow meter 30and an air flow regulating valve 31. Air is supplied from spray airheader 32 to each spray air piping 16 disposed within intake duct 13.

[0152] In FIG. 1, its air is indicated to be extracted from thedischarge portion of compressor 1, however, it may be extracted from anintermediate stage of the compressor.

[0153] Signals of a feed water quantity and a spray air quantitymeasured by the water flow meter 23 the and air flow meter 30 aretransmitted to a control unit 35. The control unit 35 computes arequired water quantity and air quantity from operating conditions ofthe gas turbine itself, and controls the feed water flow regulatingvalve 22 and the air flow regulating valve 31. Further, throughcomputation by comparing with the operation limits of the gas turbineitself, the control unit sends open/close operation signals to the feedwater pump 20 and the feed water shut-off valve 21.

[0154] Gas turbine output argumentation according to water sprayinjection quantities will be explained hereunder.

[0155] Water droplets sprayed or injected from the water spray nozzle 17each are about 10 μm by Sautor average particle diameter (S.M.D.). Waterdroplets sprayed from the water spray nozzle 17 are partly vaporizedduring flowing down within the intake duct 13 until they enter thecompressor 1. The water droplets are mixed with air introduced from thesuction chamber 11. Suction air including sprayed water droplets isintroduced into the compressor 1 and the introduced water dropletsevaporate during flowing within the compressor 1. Then, compressed airdischarged from the compressor 1 and fuel are supplied to the combustor2 and burn. Combustion gas is supplied to the gas turbine 3 and drivesit. The turbine exhaust gas is introduced into the exhaust heat recoveryboiler 72 as a heat source, and steam generated there drives the steamturbine 73. Detailed explanation will be given hereunder.

[0156] By introducing liquid droplets to be evaporated within thecompressor 1 in which the above-mentioned mixing gas flows and byevaporation of the water droplets, it is possible to further improve anefficiency under a partial load than in the above-mentioned prior arts.When the water droplets entered the inside of the compressor evaporateand the vaporization is completed within the compressor 1, the gaswithin the compressor 1 is subjected further to an adiabaticcompression. At that time, a specific heat at constant pressure of watervapor has a value of approximately two-fold of that of air in thevicinity of a typical temperature (300° C.) within the compressor,therefore, there is such an advantage that, in terms of thermal capacityconversion of the vapor to air, its operating fluid is assumed toincrease by an addition of air which is equivalent to twice the weightof water droplets to have been vaporized. That is, there is an effect tolower an outlet mixed gas (air and vapor) temperature of the compressor,or a temperature rise suppression effect. By vaporization of waterdroplets within the compressor as described above, a discharged mixedgas temperature at the outlet of the compressor is caused to drop. Sincea power of the compressor is equal to a difference in enthalpies ofmixed gas between inlet and outlet of the compressor, and since enthalpyof mixed gas is proportional to temperatures, when its outlet mixed gastemperature of the compressor is decreased, the power of the compressorcan be reduced and an efficiency can be improved.

[0157] Assuming that a compressor inlet suction temperature is T1; acompressor outlet temperature, T2; a combustion temperature, T3; and agas turbine outlet temperature, T4, a gas turbine efficiency η can beapproximated by the following equation:

η=1−(T 4−T 1)/(T 3−T 2).

[0158] Since the second term on the righthand side of equation becomessmall when the compressor inlet temperature T2 lowers to T2′ (<T2) bymixing and evaporation of the sprayed water, it is understood that theefficiency improves by water injection. In other words, a heat energy Cp(T4−T1) to be discharged outside a thermal engine of gas turbine doesnot change substantially before and after the application of theinvention, however, an input fuel energy Cp (T3−T2′) is caused toincrease by Cp (T2−T2′), i.e., corresponding to a portion of drop in thecompressor's work. On the other hand, as described above, since theportion of drop in the compressor's work is equivalent to the augmentedoutput, all of this fuel incremental portion substantially contributesto an augmentation of output of the gas turbine. That is, an augmentedoutput portion has a thermal efficiency of 100%. Therefore, the gasturbine's thermal efficiency can be improved. Since the combustiontemperature is kept constant, an efficiency of bottoming cycle is equalto that before application of the present invention, so that a totalthermal efficiency of the combined cycle can be improved.

[0159] Further, when the particle size of the spray liquid droplets islarge, the droplets impinge on blades and casing of the compressor 1 andreceive heat from the metal to evaporate, so that an effect of reducingthe temperature of working fluid may be prevented. Therefore, form thispoint of view, the liquid particle size is preferable to be small. Thespray liquid droplets have a distribution of particle size. From thepoint of view or suppressing impingement on the blades and casing of thecompressor 1 and preventing the blades from erosion, main sprayed liquidsize is made into diameter of 50 μm or less. From a point of view ofmaking less an influence of action on the blades, it is preferable to bea maximum particle diameter of 50 μm or less.

[0160] Further, liquid particles of finer particle size can bedistributed uniform in intake air and suppress occurrence of atemperature distribution within the compressor 1. From this point ofview, the particle diameter is preferable to be 30 μm or less by Sautoraverage particle diameter (S.D.M.). Since liquid droplets jetted fromthe spray nozzle have a distribution of particle size, it is not easy tomeasure the particle size by maximum diameter. Therefore, practically,the size measured by the above-mentioned S.D.M. is used. The particlesize is preferable to be small, in however, since a high precisionmanufacturing technique is required for the spray nozzle making fineliquid droplets, a lower limit that the particle size can be minimizedtechnically is a practical range of the particle size. Therefore, forexample, a lower limit in the above-mentioned main particle size, themaximum particle size or the average particle size is 1 μm. Further, thefiner the particle size is made, the larger the energy for makingparticles of such size becomes, so that the lower limit can bedetermined considering the energy used for production of fine particles.Water droplets of such a size that they float in the air and aredifficult to drop have a good condition of contact surface in general.

[0161] Air passes through the compressor 1 for a small time, and fromthe poit of view that liquid droplets are caused to be well evaporatedfor this time and an evaporation efficiency is raised thereby, S.D.M. ispreferable to be 30 μm or less.

[0162] Further, since a spray nozzle for making small diameter liquiddroplets requires a manufacturing technique of high precision, a limitthat the droplets can be made small becomes a lower limit of theparticle size or diameter. For example, it is 1 μm.

[0163] When the size of liquid droplets is too large, it is difficultfor the liquid droplets to be evaporated well in the compressor 1.

[0164] The quantity of introduced liquid particles can be adjustedaccording to a temperature, a humidity or an extent of outputargumentation as described later. For example, 0.2 wt % or more of asuction air flow rate by weight can be introduced, taking intoconsideration an evaporation quantity of sprayed water dropletsevaporating during flow from a spraying position to the compressorinlet. An upper limit of introduced water droplets is determined from apoint of view of maintaining well the function of compressor asdescribed later. For example, the upper limit is determined to be 5 wt %and an introduction range of quantity of water droplets can bedetermined that value or less.

[0165] In the intake duct 13, a quantity of air taken in the gas turbineis increased by cooling the intake air and making the density of the airhigher. Inside the compressor 1, compressed air is cooled and the powerfor the compressor 1 is decreased. Further, a working fluid for theturbine increases by evaporating water droplets within the compressor 1.

[0166] Therefore, since the power for the compressor 1 can be decreasedwhile increasing a turbine shaft output, a high output in the turbinecan be obtained. Further, it can contribute to an improvement of theefficiency.

[0167] When a water spray quantity from the spray nozzle 17 isincreasing, at first (as a first stage) a compressor inlet air quantityincreases as a compressor inlet temperature lowers, whereby an outputincreases. When a water spray quantity is being increased further, as asecond stage, an increasing rate of an output argumentation ratiochanges, the power for the compressor decreases due to lowering of acompressor inside temperature, and the output has a tendency to increaseby an increase of a gas turbine working fluid due to evaporation ofwater droplets.

[0168] This output augmenting method of the invention can be applied notonly to the combined cycle of the gas turbine and the steam turbine asindicated in FIG. 1, but also to a power plant having a single gasturbine.

[0169] Further, the sprayed water is not limited to pure water, and anymixture solution with anti-freezing solution or alcohol such asmethanol, when the atmospheric temperature is low, or with othermaterials may be used.

[0170] When a gas turbine output is increased by water spray, a waterspray quantity is within a range in which evaporation of the injectedwater droplets are completed at an upstream side of the compressor, andwater droplets are not introduced inside the compressor 1, wherebyoutput argumentation can be effected only by lowering of the compressorinlet temperature. In this case, only an output increase until theabove-mentioned first stage can be obtained. When the atmospherictemperature is low or the atmospheric humidity is high, since anevaporation quantity of water droplets within the intake duct at theupstream side of the compressor is small, an output argumentation amountis small, however, a gas flow in the compressor is not deviated from adesigned flow condition and a stable operation of the compressor can becarried out.

[0171] Further, when an output of the gas turbine is increased by waterspray, a spray nozzle 17 is provided at an inlet of the compressor 1 asin the compressor intake portion 14, in the downstream side of theintake duct 13, almost all quantity of the sprayed water is introducedin the compressor 1 at a condition of water droplets, and the waterdroplets are evaporated during flowing within the compressor, wherebythe heat of ambient air is absorbed, the temperature within thecompressor is lowered and the power for the compressor is decreased. Theoutput argumentation also can be carried out thereby. In this case, anoutput argumentation amount is smaller by such an amount that an outputincrease can be obtained by lowering the compressor inlet temperature,and the output increase can be achieved by an action of water dropletswithin the compressor. In this method, a control is simple because thewater spray conditions are not related to the atmospheric humidity, andthe number of the spray nozzles can be reduced because the water dropletsize can be relatively large. Therefore, this can be achieved by themost simple equipment as a gas turbine output augmenting mechanism bywater spray.

[0172] In this time, as indicated by line A in FIG. 2A, under normaloperation without application of water spray, outputs of the gas turbinedecline as shown by a line A in FIG. 2A since the air quantity at theinlet of the compressor which is the working medium decreases with anincrease of the atmospheric temperature. Here, in order to recover thedrop of the gas turbine's output, when water is sprayed in the upstreamside of the compressor 1, a resultant gas turbine output increases withrespect to a same atmospheric temperature as indicated by line B in FIG.2B. As a method of water injection, by predetermining line B, until anoutput of the generator 4 arrives at an output value required for agiven atmospheric temperature, the control unit 35 sends an openoperation signal to the feed water flow regulating valve 22 to increaseits water spray quantity. At the same time, in order to maintainatomized particle sizes constantly, the control unit also sends an openoperation signal to air flow regulating valve 31 in proportion to anincreased water quantity to increase the injection air.

[0173] Alternatively, as indicated in FIG. 2B, by determining aninjection planned quantity line having a predetermined margin withrespect to a water droplet limit quantity line which has been setrelative to atmospheric temperatures and humidities, water is sprayedcorresponding to the injection planned quantity. In this case where awater droplet spray limit quantity (limit line) and a planned injectionquantity are indicated, a gas turbine output has an argumentation valuecorresponding to the atmospheric temperature and humidity duringoperation and the injection water quantity.

[0174] Also, output characteristics of FIG. 2A and quantities of waterinjection (water spray) of FIG. 2B may be set with respect to the inlettemperatures of the compressor. In the case they are set up with respectto the atmospheric temperature, the temperature detector 38 and humiditydetector 75 provided in the upper stream of the water injection unit asindicated in FIG. 1 will be used. In the case they are set up withrespect to the inlet temperature of the compressor, the temperaturedetector 36 and humidity detector 61 which are provided between the downstream of the water injection unit and the upper stream of thecompressor are used. In order to improve precision of measurements,detection at a plurality of points may be made.

[0175] Further, in shift to a normal operation (for example, a ratedoperation) of the gas turbine from starting by rising r.p.m. of the gasturbine and increasing a turbine load from a partial load operation, anoutput argumentation by water spray at the upstream side of thecompressor 1 is carried out by stopping the water spray injection in atime from the starting to the load raising, and starting the water sprayafter shifting to the normal operation.

[0176] For example, water spray from the water spray nozzle 17 isstopped during the time from starting of the gas turbine to a partialload operation, and the water spray is practiced by detecting thecondition that the gas turbine reached an operation of a constantcombustion temperature under the conditions that the compressor inletguide vanes are fully opened and the combustion temperature becomesmaximum.

[0177] Alternatively, the water spray is stopped by detecting thecompressor inlet guide vane opening until the inlet guide vanes reach toan opening at a normal operation from starting, and the water spray fromthe spray nozzle 17 is started when the inlet guide vanes reach theopening at the normal operation. Thereby, misfire at the time ofstarting is prevented and the starting of high stability is carried out.Further, a starting time of the gas turbine in which a water sprayoperation is carried out can be shortened.

[0178] Otherwise, in a case where in a gas turbine which comprises acompressor 1, a combustor 2 and a turbine 3, and is provided with aspray nozzle 17 for water spray injection as mentioned above, theabove-mentioned combustor 2 has a pilot burner for diffusion combustionof fuel and a main burner for premixed combustion of premixture of fueland an oxidizer such as air, after the gas turbine has reached to arated r.p.m. at the time of starting, water spray injection is startedat a predetermined quantity by the spray nozzle 17 before a load isoutput, and it is possible to effect a combustor operation by the pilotburner and then start a load operation by the main burner. And it may bepossible to increase to a rated load. Further, in a case where aplurality of main burners are provided, it is preferable to conduct thewater spray injection even at the switching time at which the number ofthe burners used is increased, or the like.

[0179] By controlling the spray nozzle 17 in this manner, even in thegas turbine which is designed to be low in NOx concentration duringnormal operation, it is possible to suppress occurrence of NOx at theswitching time from the pilot burner by which NOx may occur temporarilyat the stating time to the main burner. Therefore, it is possible toexecute low NOx combustion. Additionally, since the water sprayinjection is started before a load is output, it is possible to stablyand smoothly increase the load.

[0180] Alternatively, it is possible that the water spray injection isstarted at a predetermined quantity by the spray nozzle 17 after anoperation by the pilot burner start to ooutput a load, and then it isshifted to a load operation to outpu load by igniting the main burner,and so on. Thereby, even with the gas turbine which is designed to below in NOx concentration during normal operation, it is possible tosuppress occurrence of NOx at the switching time from the pilot burnerby which NOx may occur temporarily at the stating time to the mainburner. Therefore, it is possible to execute a low NOx operation even atthe time of starting. Additionally, since the water spray is injectedbefore using the main burner after starting to output a load by thepilot burner, it is possible to surely generate pilot flame and increasea load.

[0181] Further, it is preferable for the spray nozzle 17 to provide a Sistrainer or Ca strainer for capturing Si or its compounds, or Ca or itscompound in feed water in the spray water piping 15. It is morepreferable to provide a strainer for capturing Si and Ca and theircompounds. It also is possible to remove roughly foreign matters in themake-up feed water tank 18, and to construct the above-mentioned foreignmatter removing filter 24 to be the above-mentioned strainer for the Si,Ca, etc. Thereby, it is possible to suppress a decrease in efficiency ofthe gas turbine according to time passage, which decrease is caused byintroduction of water droplets into the compressor, which dropletsinclude fine Si, Ca, etc. included in feed water and are injected fromthe spray nozzle 17, and by adhesion and accumulation of Si, Ca, etc. onthe compressor blades, etc. The provision of the strainer can contributeto maintaining of the efficiency of gas turbine.

[0182] Alternatively, feed water is caused to be supplied to the spraynozzle 17 through a desalting apparatus and the Si strainer or Castrainer. For example, it is preferable to cause feed water to besupplied to the spray nozzle 17 after purifying the feed water in thedesalting apparatus, and then further purifying it in the Si strainer orthe Ca strainer. The desalting apparatus removes Na, etc. in the feedwater, and the strainer captures and removes Si, etc. which is difficultto dissolve in the water.

[0183] For example, it is considered to provide the Si strainer and/orthe Ca strainer with a filter of mesh which captures Si or its compoundsof 1 μm or larger and causes Si, its compounds of smaller than 1 μm topass through. Taking account of a stable operation of the gas turbinefor a long time, it is more preferable to provide a filter of meshcapturing of Si, its compounds of 0.3 μm or larger and passing throughof them smaller than the size.

[0184] A second embodiment of the invention will be described withreference to FIGS. 1 and 3.

[0185] In the second embodiment, a water spray quantity is controlledaccording to an opening of inlet guide vanes of the compressor 1.Concretely, a water spray quantity is made more when the compressorinlet guide vane opening is larger than when small.

[0186] The present embodiment has basically the same construction as thefirst embodiment. The second embodiment is provided with a control unitin which signals of opening of the compressor inlet guide vanes areinputted in the control unit 35 and a water spray quantity is controlledaccording to the signals, in addition to the construction of the firstembodiment.

[0187]FIG. 3 shows planning lines for water injection (spray) quantitiescontrolled according to atmospheric temperatures, in which its waterspray quantity is controlled so as to differ according to openings ofthe inlet guide vanes of the compressor.

[0188] In this embodiment, its water spray injection is executed whenthe opening of its inlet guide vanes of the compressor is at anintermediate opening, namely, under a partial loading condition.According to a power demand from the plant, a partial load operationwith the load being kept constant is considered. In this case, by waterspray by the spray nozzle 17 at the upstream side of the compressor 1,power for the compressor 1 is reduced and a working fluid for theturbine 3 increases, whereby the same load operation can be maintainedwith a smaller amount of fuel. That is, a thermal efficiency at apartial load can be improved by the water spray.

[0189] In the case of intermediate openings of the compressor inletguide vanes, a spray quantity also is decreased proportionally to adecrease in a compressor inlet air flow rate. For example, a ratio ofthe water spray quantity to a compressor inlet air quantity is set orcorrected, corresponding to an angle of the compressor inlet guidevanes, independently of a rated load operating condition. Thereby, astable operation can be executed according to changes in characteristicsof the compressor and turbine from a partial load operating condition toa rated load operating condition.

[0190]FIG. 3 indicates that a larger ratio of water spray quantity canbe applied in the case of a larger opening of the compressor inlet guidevanes, however, since it depends on the types of gas turbines and thecharacteristics and operation methods of the combustors mounted thereon,it may be set so that the characteristics of each component ofindividual type of machines are reflected.

[0191] Further, a water spray quantity of the spray nozzle 17 iscontrolled on the basis of output, atmospheric pressure, etc, the sprayquantity may be controlled so as not to exceed a limit value based onthe compressor inlet guide vane openings. For example, in the case ofcontrol of water spray quantities based on the atmospheric pressure, awater spray quantity for each compressor inlet guide opening in FIG. 3is set as a water spray limit quantity of FIG. 2B, and water sprayinjection planned line with a prescribed margin can be set. In an actualoperation, when a water spray quantity limit value is determined, thecontrol unit 35 sends signals controlling the openings of the feed waterregulating valve 22 and the atomizing air flow adjusting valve 31 sothat the really effective water spray quantity does not exceed the limitvalue.

[0192] Thereby, in the case of control based on the water sprayinjection planned line, even if a rapid increase in the spray quantityoccurs because of a rapid load change or for any other reasons, the gasturbine itself can be protected by using the water spray quantity limitline.

[0193] A third embodiment of the present invention will be describedhereunder, referring to FIGS. 1, 2A, 2B, 4, 5A, 5B and 6.

[0194] In the present embodiment, a water spray quantity from the spraynozzle 17 is controlled on the basis of the atmospheric temperature andhumidity. Concretely, a water spray quantity is made more when theatmospheric temperature is higher than when low and the water sprayquantity is made larger when the humidity is lower than when high.

[0195] The present embodiment has basically the same construction as thefirst embodiment. The present embodiment is provided with a temperaturedetecting device 38 and humidity detecting device 75 at the upstreamside of the spray nozzle 17, for example within the intake chamber 11,in addition to the construction of the first embodiment. Signals fromthe detectors are input in the control unit 35 and a water sprayquantity of the water spray nozzle 17 is controlled according to thesignals. FIG. 4 indicates a water spray quantity limit line with respectto the atmospheric temperature and humidity.

[0196] In a method of water spraying, a B line in FIG. 2A has been setin advance, and a water spray quantity is increased until a requiredoutput is output. However, in a case where an extent of ageddeterioration due to contamination of the compressor of the gas turbineitself is large, and a case where a difference between individualmachines, caused by machining tolerance in the same kind of machines islarge, in order to take out of outputs of the B line, a lot of water isneeded to be injected. When an excessive amount of water is injectedinto the gas turbine, a condition of flow in the compressor is deviatedfrom a designed flow condition, a margin for surging decreases and anunstable operation of the combustor is caused. Therefore, it isprotected by the water injection limit line determined according to theatmospheric temperature and humidity, indicated by FIG. 4. In this case,in a case where the above-mentioned aged deterioration and differencebetween individual machines are large, a water spray quantity may reachthe water injection limit line before an output reaches the output ofthe B line, so that a target output can not be obtained, however, thegas turbine is protected from water injection of an excessive quantity.

[0197] Further, in a water spray method, in the case where a planningwater injection quantity has been determined in advance with respect tothe atmospheric temperature, as shown in FIG. 2B, also, the gas turbineitself can be protected with respect to a rapid increase due to anyreasons.

[0198] As shown in FIG. 4, the water spray quantity limit line isdetermined according to the atmospheric temperature and humidity. Asitems limiting a spray quantity, there may o be a water droplet quantityintroduced inside the compressor, a quantity of humidity introduced inthe combustor, a compressor inlet temperature, a pump capacity in thefeed water system, designed pressure of the feed water piping, a feedwater apparatus supply capacity, etc. The pump capacity of the feedwater system, the designed pressure of the feed water piping, the feedwater capacity, etc. of them are not referred to because usually, theircapacities are assumed to have been studied sufficiently at the time ofdesign. Therefore, as restricting conditions given by the gas turbineitself, a water droplet quantity introduced into the compressor, ahumidity quantity flowing into the combustor and a compressor inlettemperature are totalized to determine The water spray quantity limitline as indicated in FIG. 4.

[0199] The water droplets introduced inside the compressor areevaporated during flow-down inside the compressor, whereby heat isabsorbed from the ambient air and the temperature inside the compressoris lowered. Since a decrease in temperature increases the density of theair, axial flow velocity inside the compressor decreases, a velocitytriangle is deviated from a designed point at the downstream stage.During usual operation, the axial flow velocity of compressor afterstage decreases when the atmospheric temperature is low. Therefore, anoperating condition inside the compressor changes, by water spray, to acondition close to the condition of normal operation at a lowatmospheric temperature without water spray. Therefore, when theatmospheric temperature is low, an operating condition within thecompressor has exceeded an inherently allowable design range by waterinjection of a small quantity, on the contrary, when the atmospherictemperature is high, a water spray quantity can be increased. Anoperating condition deviated from a design point in this manner iscalled as mismatching within the compressor, it has reduced a margin forsurging. Since the mismatching within the compressor is caused byevaporation of water droplets within the compressor, a quantity of waterdroplets having been not evaporated in the intake duct 13 and havingentered the inside of the compressor cause a problem, and themismatching is not influenced by compressor inlet humidity due to waterevaporated in the intake duct 13. However, a quantity of evaporation ofwater droplets in the intake duct 13 is determined by the atmospherictemperature and humidity, and a compressor inlet temperature isdetermined by the quantity of evaporation of water droplets in theintake duct. Further, an allowable quantity value of water dropletsintroduced into the compressor is determined by the compressor inlettemperature, so that finally, a water spray quantity limit line withrespect to the compressor is determined by correlation of theatmospheric temperature and humidity.

[0200] On the other hand, a quantity of humidity flowing in thecombustor causes an unstable operation. Further, since the temperatureof an air flowing in the compressor decreases by evaporation of waterdroplets within the compressor, when the gas turbine is operated at thesame temperature, a quantity of injected fuel increases and backfire offlames becomes easy to occur. Therefore, since all quantity of humidityflowed in the combustor influences on an operation of combustor, a waterspray quantity limit line with respect to the combustor is determined bycorrelation of the atmospheric temperature and humidity.

[0201] A compressor inlet temperature may cause an icing phenomenon atthe compressor inlet when the atmospheric temperature is low such as inwinter season, icing occurrence is determined by the atmospherictemperature and humidity.

[0202] The water spray quantity limit line is set by associating orsynthesizing the above-mentioned matters. However, according to types ofgas turbines, considered are the case where the characteristics of thecompressor are influential over all over operational atmospherictemperatures, the case where the characteristics of the combustor areinfluential on the contrary, and the case where the characteristics ofthe compressor are influential when the atmospheric temperature is lowand the characteristics of the combustor are influential when theatmospheric temperature is high. In any of the cases, the water sprayquantity limit line is determined by the atmospheric temperature andhumidity.

[0203] After the water spray quantity limit line is determined based onthe atmospheric temperature and humidity at the time of a gas turbineoperation, the control unit 35 of FIG. 1 sends signals controllingopenings of the feed water regulating valve 22 and the atomized air flowregulating valve 31 so that a real effective water spray quantity doesnot exceed the limit value.

[0204] An effective water quantity is a water spray quantity obtained bysubtracting a quantity of drain occurred in the intake duct 13 from aquantity of water sprayed in the intake duct 13 at the upstream side ofthe compressor 1. The effective water quantity is indicated by in FIG.5B. Further, a water quantity evaporated within the intake duct 13 ofthe effective water quantity Gw3 is Gw2. A remaining water quantity Gw1is introduced into the compressor in form of water droplets. In awet-air diagram of FIG. 5B, for example in a case where a condition ofthe compressor inlet before water spraying is a point A, a water dropletquantity corresponding Gw2 is evaporated within the intake duct by waterspraying to lower a temperature of the ambient air, and the condition ofthe compressor inlet shifts to a point B. When the water spray quantityis increased further, a quantity Gw1 of water droplets which have notbeen evaporated is introduced into the compressor.

[0205] Therefore, the effective water spray quantity can be calculatedfrom an indication value Xs3 of a humidity detection device 55 for acompressor discharge air, an indication value Xs1 of a humiditydetection device 75 at the upstream side of the injection unit upstreamof the compressor, as shown in FIG. 6. The indication value of thehumidity detection device may be relative humidity, however, by settingthe device so as to put out absolute humidity, an effective water sprayquantity can be calculated only by subtracting an indication value Xs1of the humidity detection device 75 upstream of the injection unit froman indication value Xs3 of the humidity detection device 55 forcompressor discharge air. Humidity detection signals are sent to thecontrol unit 35 and an effective water quantity Gw3 is calculated.

[0206] Referring to FIG. 6, an example of the humidity detector will beexplained hereunder.

[0207] In the case where a discharge air from the compressor is used forwater atomizing spray air, the piping branches at the downstream side ofthe air shut-off valve 27 and an air pressure regulating valve 28. Abranch pipe 59 is connected to a sampling tank 56 for measuring absolutehumidity at the bottom. A flow adjusting valve 58 mounted on the branchpipe adjust a sampling air so that an ambient temperature of thehumidity sensor 55 does not rise above a durability temperature.Considering the case of occurrence of drain, a drain discharge valve 57is provided on the lower side of the sampling tank 56. Air supplied tothe sampling tank 56 rises in the tank to reach a ventilation hole 76.The above-mentioned humidity sensor 55 is inserted to the position ofthe ventilation hole 76 so that supplied air always contacts with thehumidity sensor 55. During an operation, air is always continuouslyflowed into the sampling tank 56 under this condition and measure.Further, in the case where extraction air from the middle stage of thecompressor is used as water atomizing spray air, a measuring pipe may beconnected to the discharge casing of the compressor or a combustormounting casing for directly measuring humidity.

[0208] Further, an effective water spray quantity may be calculated bysubtracting a quantity of drain in the intake duct from an indicationvalue of the water flow meter. In this case, practically, it isdifficult to detect instantaneous values of the drain quantitiesoccurred in the intake duct, so that usually an integrated value isdetected. Therefore, it is effective in the case where a continuousoperation is effected for 1 to 2 hours under the same condition in gasturbine performance test, etc. and the performance is detected bytime-averaging the value. However, it is not suitable for monitoring gasturbine operating conditions. In order to solve this problem, it iscarried out by making a function of a drain quantity occurred in theintake duct Lo a water spray quantity in advance. For example, such afunction is formed that a drain occurrence quantity increases as a waterspray quantity increase.

[0209] A fourth embodiment of the invention will be described hereunder,referring to FIGS. 1, 5A, 5B and 6.

[0210] In the present embodiment, a water droplet quantity from thewater spray nozzle 17 is controlled on the basis of the temperature ofan inlet air entering the compressor. Concretely, for example, a waterspray quantity from the water spray nozzle 17 is made more when thecompressor inlet temperature is higher than when low. Alternatively, alimit value of water spray quantity is made variable so as to becomehigher when the compressor inlet temperature is higher than when low.

[0211] Further, by inputting the compressor inlet temperature,compressor discharge humidity and humidity of compressor discharge air,a water spray quantity from the water spray nozzle 17 is controlled onthe basis of the values.

[0212] This embodiment, basically, can have a similar construction tothat of the first embodiment. That is, in addition to the constructionof the first embodiment, a temperature sensor 36 and a humidity sensor61 are provided on the intake duct 13 in the vicinity of the compressorinlet, on the downstream side of the injection unit 17. A humiditysensor 55 is provided so as to communicate with a compressor dischargeair. Signals form the sensor 55 are input into the control unit 35 and awater quantity of the water spray nozzle 17 is controlled on the basisof the signals.

[0213] In some kinds of gas turbines, the stability of combustors isvery excellent and in some cases, a factor influential to determiningthe water spray quantity limit line is mismatching within thecompressor. For example, in a case where the combustor is a type ofoil-burning diffusion combustion of which the construction is relativelysimple, the combustor can be considered to exhibit a stable operation,being little influenced by a quantity of steam contained in thecombustion air, compared with combustors of oil-burningpre-evaporation/premixing combustion and gas-burning premixing leancombustion. In this case, a water spray quantity is limited bymismatching within the compressor and lowness of compressor inlettemperature in a winter season.

[0214] A limit line of a quantity of water droplets introduced insidethe compressor with respect to compressor inlet temperature is set asshown in FIG. 5A. Thereby, water spray quantities are made variableaccording to compressor inlet temperatures. Thereby, it is possible tosuppress mismatching within the compressor, caused by compressor insideevaporation of water droplets introduced in the compressor under acondition of water droplets which remain without being evaporated in theintake duct. Thereby, the gas turbine itself can be protected. Ahumidity quantity corresponding to Gw1 indicated in FIG. 5B is limitedon the basis of a compressor inlet temperature.

[0215] Further, in the same manner as in the second embodiment, thecompressor inside water droplet introduction limit line may be set as afunction based on the compressor inlet temperature and angle of thecompressor inlet guide vanes 7.

[0216] When the system is really operated, the compressor inside waterdroplet introduction quantity limit line is determined on the basis ofcompressor inlet temperature at the time of operation of the gasturbine, the control unit 35 in FIG. 1 sends signals for controllingopenings of the feed water flow regulating valve 22 and water atomizingair flow regulating valve 31 so that a true water droplet quantityintroduced in the compressor during operation does not exceed the limitvalue.

[0217] A compressor inlet temperature is detected by the gas temperaturesensor 36 arranged between the downstream side of the injection unit andthe compressor inlet.

[0218] A compressor inside water droplet introduction quantity Gw1indicated by Gw1 in FIG. 5A, 5B can be computed from an indication valueof the humidity sensor 55 for compressor discharge air and an indicationvalue of the humidity sensor 61 set between the downstream of theinjection unit and the compressor inlet. The indication value of thehumidity sensor may be relative humidity, by setting it in advance so asoutput absolute humidity, Gw1 can be obtained by subtracting anindication value Xs2 of the humidity sensor 61 downstream of theinjection unit from an indication value Xs3 of the humidity sensor 55for compressor discharge air. Detection signals of the humidity are sentto the control unit 35 in which a compressor inside water dropletintroduction quantity Gw1 is computed.

[0219] Referring to FIG. 6, an example of a measuring device of absolutehumidity of the compressor intake portion 14.

[0220] A measuring pipe 60 for sampling humidity is connected to thebottom side of a sampling tank 62. The measuring pipe from the upperportion of the sampling tank 62 is connected to a vacuum pump 66. Airinside the compressor intake portion 14 is introduced into the samplingtank 62 and the humidity is measured. The reason that the measuring pipe60 is connected to the bottom side of the tank 62 and led to the vacuumpump from the upper portion of the tank is because of preventing thehumidity sensor 61 from contacting with drain. Further, a sampling airflow regulating valve 63 is mounted on the measuring pipe 60 and a draindischarge valve 64 is provided on the bottom of the sampling tank 62.

[0221] An absolute humidity Xs2 of the compressor intake portion 14,used for calculation of a compressor inside water droplet introductionquantity Gw1 can be measured by continuously flowing air to the samplingtank. The compressor intake portion 14 becomes negative pressure to theatmospheric pressure because of pressure loss of the intake duct 14. Useof the measuring means of this construction prevents that an air flowsback from the atmosphere into the compressor intake portion 14 andmeasurement of the absolute humidity of the compressor intake portion 14is impossible, and make it possible to execute a suitable measurement.

[0222] Further, as for a compressor inside water droplet introductionquantity Gw1, an effective water spray quantity is directly obtained bysubtracting a drain quantity in the intake duct from an indication valueof the water flow meter, and the quantity Gw1 can be computed bysubtracting therefrom a quantity of water evaporated within the intakeduct. In this case, the quantity of water evaporated within the intakeduct is calculated by subtracting an indication value Xs1 of thehumidity sensor 75 upstream of the injection unit from an indicationvalue Xs2 of the humidity sensor 61 downstream of the injection unit.The quantity of drain occurred within the intake duct can be made, inadvance, into such a function that it increases as a water sprayquantity increases, for example.

[0223] Further, it is preferable to provide a mode switch by which wateris sprayed according to months and days, and time. As for a condition ofmonths and days and time, from April to November, from nine o'clock to18 o'clock as the time of a large electric demand or the time when a gasturbine output lowers according to elevation of the atmospherictemperature are taken as the condition. Thereby, the time for use of theoutput augmenting apparatus can be made clear, so that it is easy tomaintain and manage the equipment, etc.

[0224] A fifth embodiment of the present invention will be describedhereunder, referring to FIGS. 1, 8, 9, 10, 11A and 11B.

[0225] In this embodiment, the intake duct 13 is provided with aplurality of water spray nozzles 17, and it further comprises a waterfeed apparatus, main feed water piping in which water flows from thefeed water apparatus, a feed water header causing water from the mainfeed water pipe to branch into a plurality of feed water pipes.

[0226] In the case of two-fluid nozzles, air supplied to the water spraynozzles, and a construction therefor comprises an air supply apparatus,a main air pipe in which air from the air supply apparatus flows and anair supply header causing air supplied from the main air pipe to branchinto a plurality of air supply pipes in the same manner as in the caseof water. The air supply pipes are connected to the water spray nozzles.

[0227] In this manner, the water spray nozzles 17 are divided into aplurality of systems, and the systems ( the number of the water spraynozzles)used are controlled so that the number of the systems in whichwater is supplied becomes larger when a water spray quantity is morethan when less.

[0228] The control unit controls so as to change the number of the waterspray nozzles 17 used for water spray, corresponding to water sprayquantities.

[0229] The present embodiment, basically, may have a similarconstruction to that of the first embodiment. That is, in addition tothe first embodiment construction, a temperature detector 36 andhumidity detector 35 are provided, for example, on the intake duct 13 inthe vicinity of the compressor inlet at the downstream of the waterspray nozzles 17. The humidity detector 55 is provided so as tocommunicate with compressor discharge air. Signals form the humiditydetectors are input into the control unit 35 to control a water quantityof the water spray nozzles 17 on the basis of the signals.

[0230] Water spray characteristics in a case where two-fluid nozzles areused are shown in FIG. 8. A water/air ratio is defined by a volume ratioof atomizing air quantity and water spray quantity. Since spray pressuredecreases as a water quantity decreases under the condition that an airwater ratio is constant, particle size of water droplets becomes large.Further, when one-fluid nozzles are used, also, since spray pressuredecreases as a water quantity decreases, particle size of water dropletsbecomes large.

[0231] When water droplets sprayed from the water spray nozzles 17becomes large, erosion occurs by impingement of the water droplets onthe compressor blades, there is the possibility that the performance ofthe compressor is worsened. However, when the size of the water dropletsis sufficiently small, the droplets do not impinge on the compressorblades, but they flow with flowing air and evaporate within thecompressor. In order to pass water droplets through between thecompressor blades without impingement on the compressor blades, althoughthere is a difference by a design condition such as air flow velocityand shape inside the compressor, the above-mentioned average particlediameter is smaller than a prescribed size. For example the diameter ismade to be 20 μm or less. In the intake air humidification coolingsystem, even if a water spray quantity changes, it is preferable thatthe particle diameter of the water spray droplets is a prescribed valueor less.

[0232] In order to solve the problem, as shown in FIG. 1, when a waterspray quantity is small, the flow regulating valves 26 communicatingwith the spray water pipes are controlled so that a part of the feedwater valves 26 are opened and the others are closed so as to supplywater to a prescribed part of the spray water pipes 15 communicatingwith the feed water header 25. In the same manner, air distributed bythe atomizing air header 32 is controlled by the air flow regulatingvalves 33. When a water spray quantity is increased, the number of theopened flow regulating valves communicating with the spray water pipesis increased. The number of the air flow regulating valves 33 also isincreased corresponding to the number of the feed water flow regulatingvalves 26.

[0233] Further, a construction until the spray nozzles may be made byincreasing the number of feed water headers as shown in FIG. 9,constructing a main feed water header 77 and auxiliary feed waterheaders 78,79, and providing feed water flow regulating valves 80 and 81and feed water flow meters 82 and 83 on feed water lines connected tothe auxiliary feed water headers 78, 79.

[0234] In this Figure, also, only one spray water pipe branched from theauxiliary header 78, 79 is illustrated.

[0235] When a water spray quantity is small, only one auxiliary feedwater header 78 is used and so on, whereby water is sprayed by a part ofthe number of installed water spray nozzles 17. Thereby, spray pressureof the spray nozzles can be maintained high, whereby such control ispossible that water supply is in a water spray quantity range in whichwater droplets become a certain size or less in the nozzle spraycharacteristics of FIG. 8. Further, the spray pressure increases withincrease in the water spray quantity, however, in order not to exceedthe designed pressure in the feed water system, two of the auxiliaryfeed water headers 78, 79 are used and so on when the spray pressurebecomes higher than a certain value, whereby the number of the waterspray nozzles 17 used for spray is increased. The number of theinstalled auxiliary feed water headers is determined by the designconditions such as the maximum water quantity, the number of water spaynozzles, the minimum and maximum water spray pressures, etc. In FIG. 9,the feed water system is illustrated in which two auxiliary feed waterheaders are used.

[0236] Further, even in the case where the water spray quantity is smallas a whole, a stable output augmenting operation can be effected byincreasing a water spray quantity per one nozzle and suppressingvariation in average particle diameter of the water droplets, caused byvariation of the water spray quantity.

[0237] An operation method in which two auxiliary feed water headers areused is shown in FIG. 10. In the case of the maximum water quantity100%, one auxiliary feed water header is used until the water quantityreaches to 50%. As a switching point at a water quantity of 50%, byusing the second auxiliary feed water header, the two headers are usedsupplying water of the same quantity to then until the water quantityreaches to 100%.

[0238] In this manner, according to the present embodiment, even ifthere is variation in water spray quantity, water droplets of desiredparticle size can be stably obtained, and an operation of variableoutput argumentation can be carried out while keeping the soundness ofthe apparatus and devices.

[0239] Further, by providing the feed water header with a plurality offeed water pipes 15 without installing auxiliary feed water header, andby arranging a feed water flow regulating valve and flow meter at thedownstream side of the main feed water header of the feed water system,it is possible to change the number of water spray nozzle pipes beingoperated.

[0240] Further, by providing a feed water flow regulating valve for eachwater spray nozzle of the feed water system and providing air flowregulating valve for each water atomizing air nozzle of the air supplysystem, without providing auxiliary feed water header, it is possible tochange the number of water spray nozzles being operated.

[0241] A sixth embodiment of the present invention will be describedhereunder, referring to FIGS. 1, 5, 6, 11A and 11B.

[0242] In this embodiment, a water quantity or air quantity supplied tothe water spray nozzles 17 are controlled according to a water sprayquantity.

[0243] The present embodiment, basically, may have a similarconstruction to that of the first embodiment. In addition to theconstruction of the first embodiment, the feed water outlet flowregulating valve 26 and atomizing air header flow regulating valve 33are controlled, according to a water spray quantity, so as to increaseand decrease an air supply quantity so that an air water ratio becomesconstant (so as to suppress a variation).

[0244] Thereby, water droplets of a certain particle size can beobtained (in the case of a relatively large water quantity it isremarkable) while suppressing an air flow rate to be small. When air istaken from the compressor, a lot of air among the intake air can besupplied to the combustor, and an operation so as to improve output andefficiency can be carried out.

[0245] Further, the feed water outlet flow regulating valve 26 andatomizing air header flow regulating valve 33 are controlled, accordingto a water spray quantity, so as to increase and decrease an air supplyquantity so that a variation of an air water ratio may be suppressedand, preferably, a air water ratio becomes constant.

[0246] Concretely, an air water ratio is controlled to be small when awater spray quantity is larger than when small.

[0247] Thereby, water droplets of a certain particle size can beobtained (in the case of a relatively large water quantity it isremarkable) while suppressing an air flow rate to be small. When air istaken from the compressor, a lot of air among the intake air can besupplied to the combustor, and an operation so as to improve output andefficiency can be carried out.

[0248] Nozzle spray characteristics in which particle size of waterdroplets is made constant are indicated in FIG. 11A. Since it isnecessary to make an air water ratio larger according to decrease in thewater spray quantity in order to make the particle size constant, forexample, a relationship between a water spray quantity and an atomizingair quantity or an air water ratio, for making the particle sizeconstant, have been input in advance into an arithmetic unit, and thenby measuring a water spray quantity by the feed water flow meter andcalculating a necessary atomizing air quantity, the atomizing airquantity is controlled. Thereby, variation of particle size according towater spray quantity can be suppressed. Therefore, erosion occurrence onthe compressor blades by impingement of the water droplets on the bladescan be prevented and a variable output augmenting operation can beexecuted while maintaining the soundness of the apparatus and devices.

[0249] Alternatively, even by increasing and decreasing a feed waterquantity, even by changing the feed water header outlet flow regulatingvalve 26 so as to make the air supply quantity constant, according to awater spray quantity, the atomizing air header flow regulating valve 33is controlled to be constant. Thereby, a variable output augmentingoperation can be executed while maintaining the soundness of theapparatus and devices by a simple control.

[0250] For example, spray nozzle characteristics when an atomizing airquantity is made constant is indicated in FIG. 11B. As indicated in FIG.11B, an air flow quantity has be determined on the basis of the airwater ratio at a water quantity of 100% of the water nozzle, air of aconstant quantity is supplied to the water spray nozzle irrespective ofvariation in the water spray quantity. Thereby, the particle size ofsprayed water droplets becomes always a rated size or less, and avariable output augmenting operation can be executed while preventingoccurrence of erosion by relatively simple control.

[0251] A seventh embodiment of the present invention will be describedhereunder, referring to FIG. 1 and 9.

[0252] In this embodiment, when water spray starts, a control is carriedout so that first, supply of atomizing air is started, and then supplyof atomized water is started. Further, when the water spray is stopped,the control is executed so that first, the supply of atomized water isstopped, and then the atomizing air supply is stopped. Further, at thetime of a water spray operation, control devices for feed water and feedair supplied to the spray nozzles are controlled so as to be throttledon the basis of a gas turbine trip signal.

[0253] The present embodiment, basically, may have a similarconstruction to that of the first embodiment. Concretely, the followingcontrol is executed.

[0254] When the water spray is started on the basis of a water injectioninstruction, first, the extraction air shut-off valve 17 of theatomizing air system is opened. At this time, air flows by a quantity ofthe air exhausted from a cyclone separator 29. Next, the air flowregulating valve 84 is opened so as to flow by an initial set flow rateand the air flows into the spray nozzle 17. After the air passagethrough the nozzle 17 is completed, the feed water system is started.The feed water pump 20 is started, the feed water shut-off valve 21 isopened, and water of an initial set flow rate is flowed by operation ofa feed water flow regulating valve 80. According to this process, thespray water is atomized by water atomizing air sprayed, and sprayed fromthe spray nozzle 17. Then, a spray water quantity is gradually increaseduntil the water quantity reaches a water injection instruction value.

[0255] Further, in the case where a plurality of auxiliary feed waterheaders and auxiliary atomizing air headers are used as shown in FIG. 9,a switching operation is executed at a water quantity of 50% in FIG. 10according to an increase in water quantity, the air flow regulatingvalve 84 is opened to flow air of a set flow rate, and then the feedwater flow regulating valve 81 is operated to open. In this manner, byflowing air of a set flow rate first, it is possible to maintain a waterdroplet atomizing characteristics even in the process of increasing aquantity of water.

[0256] A process of stopping the water spray is explained, referring toFIG. 9. First of all, the feed water shut-off valve 21 is closed, andthen the feed water flow regulating valves 80, 81 are fully closed.Here, since in some cases, water downstream of the feed water flowregulating valve is sprayed by injection of atomizing air for severalminutes, after time passage for a certain time after stopping of supplyof feedwater, the extraction air shut-off valve 27 is closed, and theair flow regulating valves 80, 81 are fully closed. In this manner, inthe water spray stopping operation process, also, the air spraying isstopped after the feedwater is stopped, whereby the water atomizingcharacteristics can be maintained after the stopping.

[0257] Thereby, water spray starting or stopping operation can beexecuted while maintaining the soundness of the apparatus and devices.

[0258] Further, at the time of gas turbine trip during the water sprayoperation, the feedwater shut-off valve 21 and the extraction airshut-off valve 27 are fully closed by a trip signal. In this case,although atomizing air sprayed is lacked and water of large particlediameter in the feed water duct is sprayed or the water drops bydifference in weight, it occurs for a short time, so that such a problemas erosion of the compressor blades is not caused thereby.

[0259] Further, concretely, first, an instruction of stopping waterspray is issued on the basis of a signal of gas turbine trip. Then aninstruction of decreasing the compressor inlet guide vane opening isissued. Thereby, the soundness of the plant can be secured further atthe time of gas turbine trip.

[0260] An eighth embodiment of the present invention will be describedhereunder, referring to FIGS. 1, 12A and 12B.

[0261] In this embodiment, by detecting a temperature distribution ofair at the inlet of the compressor 1 in a peripheral direction, acontrol is carried out so that a temperature deviation does not exceed aprescribed value.

[0262] The present embodiment, basically, may have a similarconstruction to that of the first embodiment. In this embodiment, aplurality of temperature detectors 36 are further arranged on the intakeduct 13 as shown in the section taken along line A-A of FIG. 12A.

[0263] Water droplets 40 injected from injection nozzle 17 are partlyvaporized within the intake duct 13 thereby dropping the temperature ofambient air, and are introduced into compressor 1. At this time, when awater quantity supplied from some of a series of water spray pipes 15 isinsufficient due to clogging or the like of spray nozzle 17, adifference in measured temperatures occurs when intake duct airtemperature detectors 36 are provided at a plurality of positions. Sincenonuniformity of flow at the intake portion will normally cause unstableoperation of the compressor, uniformity in the temperatures is alsorequired to be ensured. Nonuniformity or deviation of temperature in thecircumferential direction at the intake portion of the compressorimplies that correcting revolution numbers of the compressor differ inthe circumferential direction, which causes mismatching between stagecharacteristics within the compressor.

[0264] Further, in the case where the temperature deviation at the inletof the compressor is due to the above-mentioned deviation of water flow,there occurs a difference in amounts of water droplets to be introducedinto compressor 1 without having been vaporized within intake duct 13 inthe circumference direction of the intake portion. Since water dropletsintroduced into compressor 1 serve to drop ambient temperatures of amain air stream within compressor 1 by being vaporized therein, when adeviation of water droplet distribution in the circumference directionis large, there occurs that a temperature drop in a particular portionwithin the compressor becomes large whileas a temperature drop inanother portion becomes small, thereby further deteriorating thecircumferential temperature deviation within the compressor. Therefore,there may be considered such a case where an excess drift waterexceeding the limit value is unintentionally allowed to flow partiallywithin the compressor although the operation within the injection waterlimit line is intended.

[0265] Further, when use of the inlet temperature and humidity ofcompressor 1 is considered for the control of water quantity, theabove-mentioned temperature deviation will affect the control of waterquantity, and will cause such a case where an excess quantity of waterover the water quantity limit value is injected, or contrarily anadequate amount of water which is required for obtaining a target gasturbine output cannot be injected.

[0266] A value is predetermined arbitrarily as an allowable value fortemperature deviations, temperature signals at a plurality of pointsdetected by air temperature detector 36 indicated in FIGS. 12A, 12B aretransmitted to control unit 35, then in the case when a temperaturedeviation exceeds the predetermined allowable value, the control unitcontrols the opening of the feed water header outlet flow regulatingvalve 26 such that a supply water quantity to be supplied from eachwater spray pipe 15 to its spray nozzle 17 becomes constant therebysuppressing the deviation within the allowable value. For example, insuch a case where injection nozzle 17 is clogged by foreign matters suchas rust accumulated in the piping, since a feed water pressure in eachwater spray piping 15 is the same, and since a water quantity to flowinto a particular water injection piping having many clogged nozzlesdecreases than quantities in other water spray piping, there results ina temperature deviation. Therefore, in order to balance water flowsamong the water spray piping, openings of the feed water header outletflow regulating valves 26 of other water spray piping without beingsubjected to clogging are decreased. Thereby, the temperature deviationat the inlet of the compressor is eliminated upon balancing of flows inrespective water spray piping 15. However, since the feed water quantitydrops due to the decreased opening of the feed water header outlet flowregulating valve 26, the control unit 35 sends an open valve operationsignal to the feed water flow regulating valve 22 to raise the pressureof the feed water header such that an indication by water flowmeter 23increases to a target water flow. Further, when the feed water pressureis raised, a quantity of water droplet atomizing air becomesinsufficient, thereby, the control unit 35 sends an open valve operationsignal also to the air flow regulating valve 31 to raise its supplypressure and control the air flow to become at a target value.

[0267] Thereby, partial occurrence of icing or stalling is suppressedand a high output operation will be possible while securing thesoundness of the apparatus and device.

[0268] Further, instead of the construction shown in the section of A-Aof FIG. 12A, an air temperature detector 37 can be arranged at theupstream side of the compressor inlet guide vanes as shown in thesection B-B of FIG. 12B. The section B-B is a section upstream of thecompressor inlet guide vanes 7. This construction can have a similareffect to the construction shown by the section A-A. The air temperaturedetectors 37 are arranged at the inlet of the compressor inlet guidevanes 7 at an interval in the peripheral direction, preferably, at anequi-interval, whereby more precise temperature deviation can bedetected, abnormality of the apparatus and devices can be detectedprecisely and maintenance of the apparatus and the devices can beeffected.

[0269] Although an allowable value of preset temperature deviationshould be set to different values according to types or kinds of gasturbines, in the present invention, it can be set to 15° C. or lower.

[0270] An example of operation of the present invention will bedescribed hereunder, referring to FIGS. 1 and 13.

[0271]FIG. 13 indicates icing limit at the inlet of the compressor 1.

[0272] For example, in the case of atmospheric condition being 10° C.and relative humidity being 30%, it is located at point A in FIG. 13.Upon vaporization of a portion of injected water between the downstreamside of the water injection unit and the upstream side of thecompressor, an inlet temperature of the compressor 1 drops theoreticallyto 3.5° C. at point C with a relative humidity of 100%. However, an airvelocity in the vicinity of the compressor inlet guide vane 7 isaccelerated to approximately 200 m/s. Thereby, a static temperature ofair drops, and a recovery temperature on the surface of blades of thecompressor inlet guide vane 7 decreases by 2-3° C. Therefore, there is apossibility for water droplets introduced into the compressor to freezeon the wall surface of casing and on the compressor inlet guide vane 7.

[0273] When an icing phenomenon takes place, the output of the gasturbine drops due to a decrease in quantity of intake air to thecompressor 1. Further, there is a possibility that the compressor bladeis damaged by periodical scattering of grown-up ice. Still further inthe case where partial icing in the circumferential direction at theinlet of the compressor takes place, intake air quantities sucked intothe compressor become uneven in the circumferential direction, therebycausing unbalanced vibrations of a rotating portion of the gas turbineor unstable operation of the compressor.

[0274] In actual operation, it is required to preset a lower limit valueof temperatures, which should be determined with an adequate margin inconsideration of an opening of compressor inlet guide vane 7 underoperation, a temperature deviation in the circumferential direction inthe inlet of compressor 1, and respective variations and precision ofmeasurements of the air temperature detectors 36. In this embodiment, itis preset at 15° C. In FIG. 13, for example, the lower limit value isset at 5° C., and a region 3 which is lower than 5° C. is defined as awater spray prohibit region. Therefore, in the case of FIG. 13, a waterspray allowable region is until point B in which an inlet temperature ofthe compressor 1 is 5° C. and a relative humidity is 75%.

[0275] In FIG. 13, in the case where an atmospheric condition is locatedin region 1, it does not occur theoretically that any inlet temperatureof the compressor 1 becomes lower than 5° C., thereby eliminating anywater spray limitation against icing. Further, in the case where itsatmospheric condition is located in region 2, since it is possible forthe inlet temperature of the compressor 1 to drop below 5° C. and enterregion 3, the water quantity is controlled such that the inlettemperature of the compressor 1 will not drop below 5° C. At this time,since any partial icing at the inlet of the compressor should not beallowed, the same water flow control as in the first embodiment of theinvention is executed such that every detected values of temperaturesignals of air temperature detectors 36 will not drop below 5° C.

[0276] When the atmospheric condition enters region 3 of FIG. 13 duringoperation, namely, when a dry bulb temperature of the atmosphericcondition becomes below 5° C., since icing phenomenon starts in two orthree minutes, it becomes necessary to stop water supply speedily,thereby, the control unit 35 sends a closing valve operation signal tothe feed water shut-off valve 21. Otherwise, the feed water pump 20 issubjected to emergency stop.

[0277] In the case where the atmospheric condition of FIG. 6 is inregion 2, that is, a dry bulb temperature of the atmosphere is below 5°C., since a water spray quantity for control in actual operation becomessmall, an increase in output of the gas turbine to be augmented islimited, thereby providing less advantage. Therefore, without allowingthe water control to be executed to the verge of icing, when the wetbulb temperature drops below 5° C., the control unit 35 sends a closingvalve operation signal to the feed water shut-off valve 21. Otherwise,the feed water pump 20 is subjected to emergency stoppage. In this case,the possibility of icing is completely eliminated, thereby ensuring asafer operation.

[0278] In the suction chamber 11 in FIG. 1, the atmospheric conditiondetector 38 and atmospheric humidity detector 75 are installed. Theatmospheric condition detector 38 and atmospheric humidity detector 75may be placed anywhere in the upstream side of the water injection unitprovided that they are not affected by rain drops. As a result ofdetection by the atmospheric temperature detector 38 and atmospherichumidity detector 75, it is found in which region of FIG. 13 to bepositioned. Further, a result of detection by the compressor inletsuction duct air temperature detector 36 and compressor inlet gashumidity detector 61 of FIG. 13 may be used as well. Further, in thecase where a signal of detected humidity is a relative humidity, it maybe converted to an absolute humidity in control unit 35.

[0279] A ninth embodiment of the present invention will be describedhereunder, referring to FIG. 1, 14, 15 and 16. FIG. 14 is a schematicdiagram showing an example of operational condition detectorssurrounding the gas turbine itself relating to the water flow control.

[0280] The present embodiment, basically, may have the construction ofthe first embodiment. In addition to the construction, as shown in FIG.14, a compressor inlet total pressure gauge 39 is provided in the upperportion of the compressor air intake portion 14, a wall pressuredetector 43 is provided in an inlet casing of the compressor inlet guidevane 7, a compressor wall pressure variation detecting pressure sensor44 is provided in an intermediate stage of the compressor, a compressordischarge portion temperature detector 45 and a compressor dischargepressure detector 46 are provided at a discharge portion of compressor1, a gas turbine exhaust gas temperature detector 47 is provided in agas turbine exhaust diffuser 8, a bearing vibration detector 42 isprovided on compressor frontal bearing 6, a bearing vibration detector52 is provided on a turbine exhaust side bearing 9, a metal temperaturedetector 41 is provided on a thrust bearing 5, and a drain detectionlevel switch 48 is provided in the compressor air intake portion. It isnot necessary to provide all the above-mentioned detectors, etc.

[0281]FIG. 15 indicates changes in the operating conditions of theentire gas turbine under occurrence of icing phenomena.

[0282] Water spray injection starts at point A in FIG. 15, and inaccordance with an increasing quantity of water spray, a compressorinlet temperature decreases. However, in such a condition where itsatmospheric temperature is too low, an icing phenomenon starts to takesplace from point B, thereby affecting the overall performance of the gasturbine. When icing phenomenon takes place in the inlet of thecompressor, ice grows on the surfaces of inlet guide vane 7 and thecasing, thereby decreasing a frontal annulus area of the compressor, andthereby decreasing a compressor inlet air flow. When the compressorinlet air flow decreases, a gas turbine output drops. Further, since avelocity of air flow in the inlet of the compressor drops, a pressure onthe wall of casing in the inlet portion of compressor inlet guide vane 7increases. A decrease in amounts of air flow at the inlet of thecompressor will result in a decrease in amounts of air flow at the inletof the gas turbine, thereby decreasing a discharge pressure of thecompressor so far as the operation is maintained at a constantcombustion temperature. When the discharge pressure of the compressordrops during operation at the constant combustion temperature, anexhaust gas temperature of the gas turbine increases. In the case wherean interstage mismatching occurs within the compressor triggered by theicing phenomenon, an adiabatic efficiency of the compressor dropsremarkably, thereby increasing the discharge temperature of thecompressor.

[0283]FIG. 16 indicates changes in overall operational conditions of thegas turbine under occurrence of a stall Phenomenon.

[0284] Water injection is started from point A in FIG. 16. With anincreasing quantity of water injection, the inlet temperature of thecompressor decreases, and its output starts to increase. However, in thecase there is a non-uniform temperature distribution at the inlet of thecompressor, a non-uniform distribution of water droplets introduced intothe compressor in the circumferential direction thereof, any interstagemismatching within the compressor due to excess water injection thereinor the like, there is a possibility that a blade stalling phenomenonwithin the compressor may result in. When there occurs a stallingphenomenon of blades, a variation of wall pressures of the compressorincreases due to an unstable flow by the stalling. Since a stalled bladeregion inhibits its air flow, the quantity of inlet air of thecompressor decreases. The decrease in the quantity of the inlet air ofthe compressor causes to decrease the gas turbine's output. Further,since an air flow velocity at the inlet of the compressor is caused todecrease, a casing wall pressure in the inlet portion of compressorinlet guide vane 7 increases. Since the decrease of the inlet airquantity of the compressor results in a decrease in the inlet air to thegas turbine, the discharge pressure of the compressor is also decreasedso long as operation at a constant combustion temperature is maintained.When the discharge pressure of the compressor is decreased underoperation at a constant combustion temperature, an exhaust gastemperature of the gas turbine increases. The adiabatic efficiency ofthe compressor drops remarkably due to the stalling phenomenon, therebyincreasing the discharge temperature of the compressor. Along with arise of variation level of compressor wall pressures, a vibration in arotating portion of the gas turbine increases as well thereby increasinga value of vibration of its bearing.

[0285] Although, as mentioned above, the gas turbine itself isessentially protected by the spray water quantity limit lines, in thelong run there may be considered such a case where use of the same limitlines alone may not be able to ensure the protection of the gas turbineitself in consideration of influences such as decreases in surge marginsdue to ageing deteriorations of the compressor and the like. Therefore,it becomes necessary for the operational conditions in the circumferenceof the gas turbine inclusive thereof to be detected and monitored foreach item of detection with respect to its predetermined allowable valueof variation.

[0286] (1) Since the stall phenomenon within the compressor and theicing phenomenon on the inlet guide vane 7 of the compressor result inthe drop of the compressor inlet air quantity, it becomes possible todetect their occurrences by monitoring the compressor inlet airquantity. In practical operation, in case the compressor inlet airquantity drops lower than the predetermined allowable value within apredetermined period of time, the control unit 35 sends a signal to thefeed water flow regulating valve 22 to decrease its opening so as todecrease the water injection quantity. Further, in case the allowablevalue for variation is exceeded, water supply may be shut off to protectthe gas turbine. In this case, the control unit 35 transmits a closingoperation signal to the feed water shut-off valve 21. Otherwise, thefeed water pump 20 may be stopped in emergency.

[0287] Here, the compressor inlet air quantity is calculated, forexample, using signals from the compressor inlet total pressure gauze 39installed in the upper portion of the compressor intake portion 14, theinlet portion casing wall pressure detector 43 in the inlet ofcompressor inlet guide vane 7, and a temperature signal from the intakeduct air temperature detector 36.

[0288] Thereby, the icing or stalling phenomena can be surely detected,so that the soundness of the gas turbine can be surely secured.

[0289] (2) Monitoring of the inlet portion casing wall pressure in theinlet of compressor inlet guide vane 7 is executed in order to detectthe phenomena of stalling within the compressor and icing on thecompressor inlet guide vane, and to achieve the safety operation of thegas turbine. In case the compressor inlet flow decreases, theabove-mentioned compressor guide vane inlet casing wall pressureincreases. For example, at stoppage of the gas turbine, a compressorinlet flow quantity becomes 0, at this time, its casing wall pressure isin the condition of atmospheric pressure which is a maximum value. Withan increasing speed of the gas turbine and with an increase in thequantity of the inlet air flow, a velocity of air increases, therebydecreasing its static pressure, or its casing wall pressure drops.

[0290] The above-mentioned compressor guide vane inlet casing wallpressure is used for calculation of the compressor inlet air quantity.Both of them can be approximated in a linear function with an adequateprecision being ensured in an actual extent of the gas turbineoperation. Therefore, there is such an advantage that when theoperational condition of compressor 1 becomes unstable, feed water canbe shut off immediately only by referring to the compressor guide vaneinlet casing wall pressure, without need of executing the result ofcalculation of the compressor inlet air quantity.

[0291] In an actual operation, the casing wall pressure detector 43 isinstalled in the inlet portion of compressor inlet guide vane 7, and incase where the above-mentioned compressor inlet casing wall pressureincreases over the predetermined limit value for a predetermined periodof time, the control unit 35 is caused to send a signal to the feedwater flow regulating valve 22 to decrease the opening thereof so as todecrease the quantity of water injection. Further, in the case ofexceeding the allowed value for variation, water supply may be shut offto protect the gas turbine itself. In this case, the control unit 35sends a closing operation signal to the feed water shut-off valve 21.Alternatively, the feed water pump 20 may be stopped in emergency.

[0292] Thereby, the detectors can be easily installed, the phenomenon oficing or stalling can be easily detected and the soundness of the gasturbine can be secured.

[0293] (3) Monitoring of the compressor discharge pressure is executedin order to detect the phenomena of stalling within the compressor andicing on the compressor inlet guide vane, and achieve the safetyoperation of the gas turbine. When the compressor inlet flow quantitydecreases, the above-mentioned compressor discharge pressure drops solong as under operation at a constant combustion temperature. Arelationship between the compressor inlet air flow and the compressordischarge pressure can be approximated by a linear function with anadequate precision in the case of operation at the constant combustiontemperature. Therefore, there is such an advantage that when theoperational condition of the compressor 1 becomes unstable, water supplycan be shut off immediately based on the compressor discharge pressurewithout need of executing the result of calculation of the compressorinlet air flow quantity.

[0294] In actual operation, the compressor discharge pressure detector46 is installed in the discharge portion of compressor 1, and in casethe above-mentioned compressor discharge pressure drops below thepredetermined limit value within a predetermined period of time, thecontrol unit 35 is caused to send a signal to the feed water flowregulating valve 22 to decrease its opening so as to decrease thequantity of water injection. Further, in case the allowable value ofvariation is exceeded, water supply may be shut off for protection ofthe gas turbine. In this case, the control unit 35 sends a closingoperation signal to the feed water shut-off valve 21. Otherwise, thefeed water pump 20 may be stopped in emergency.

[0295] Since the pressure level is high and a change in the level can berapidly detected, the soundness of the gas turbine can be rapidlysecured upon occurrence of an icing or stalling phenomenon.

[0296] (4) Monitoring of the compressor discharge temperature isexecuted in order to detect the phenomena of stalling within thecompressor and icing on the compressor inlet guide vane, and to ensurethe safety operation of the gas turbine. In case there occurs a stall oricing phenomena with an increasing water injection quantity, since theadiabatic efficiency of the compressor decreases, the compressordischarge temperature does not drop but remains constant or increasesdespite the increased quantity of water. Inherently, the inlettemperature of the compressor should decrease by water injection, and inaddition, since the temperature of the main air stream is to bedecreased by vaporization of water droplets having been introduced intothe compressor, the compressor discharge temperature should dropapproximately in a linear relationship with the quantity of injectedwater. Therefore, an instance that the compressor discharge temperaturedoes not drop indicates that the compressor efficiency has dropped dueto unstable operation within the compressor.

[0297] In actual operation, the compressor discharge temperaturedetector 45 is installed in the discharge portion of the compressor 1,and in case the above-mentioned compressor discharge pressure dropsbelow the predetermined limit value within the predetermined period oftime, the control unit 35 is caused to send a signal to the feed waterflow regulating valve 22 to decrease its opening so as to decrease thequantity of water injection. Further, when in excess of the allowablevalue of variation, water supply may be shut off for protection of thegas turbine itself. In this case, the control unit 35 sends a closeoperation signal to the feed water shut-off valve 21. Otherwise, thefeed water pump 20 may be stopped in emergency.

[0298] (5) Monitoring of the compressor adiabatic efficiency is executedin order to detect the stall phenomenon within the compressor and icingphenomenon on the compressor inlet guide vane, as well as to detect theinterstage mismatching within the compressor, and to attain the safetyoperation of the gas turbine. Since the compressor discharge temperaturedrops with an increasing quantity of water injection, apparently, thecompressor adiabatic efficiency increases. However, where there occursany stall or icing phenomena with an increased quantity of waterinjection, the adiabatic efficiency of the compressor decreases.Further, a subtle mismatching between interstages within the compressorwhich does not appear remarkably from a mere detection of theabove-mentioned compressor inlet flow quantity, discharge pressure anddischarge temperature, can be detected more clearly by the compressoradiabatic efficiency. The compressor discharge temperature which issimple because it does not need calculation thereof tends to be affectedby a drop of the compressor discharge pressure when detectingdeterioration of performance of the compressor. Therefore, there is sucha case where the drop of performance of the compressor cannot bedetected after all without calculation of the compressor adiabaticefficiency.

[0299] In practical application, on the basis of measurements by thecompressor inlet total pressure gauge 39 and intake duct air temperaturedetector 36 which are installed in the upper portion of compressorintake portion 14, and by the compressor discharge temperature detector45 and compressor discharge pressure detector 46 which are installed inthe discharge portion of compressor 1, when it is found that theabove-mentioned compressor adiabatic efficiency has dropped more thanthe predetermined limit value within the predetermined period of time,the control unit 35 is caused to send a signal to the feed water flowregulating valve 22 to decrease its opening so as to decrease thequantity of water injection. Further, in case it is in excess of theallowable value of variation, water supply may be shut off forprotection of the main body of the gas turbine. In this case, thecontrol unit 35 sends a closing operation signal to the feed watershut-off valve 21. Otherwise, the feed water pump 20 may be stopped ofits operation in emergency.

[0300] Thereby, even if the atmospheric temperature changes, occurrenceof icing or stalling phenomena can be detected easily, whereby thesoundness of the gas turbine can be easily secured.

[0301] (6) Monitoring of gas turbine exhaust gas temperatures isexecuted for detection of the stall phenomenon within the compressor andthe icing phenomenon on the compressor inlet guide vane, and forattainment of the safety operation of the gas turbine. Upon lowering ofthe compressor inlet flow quantity, the above-mentioned compressordischarge pressure drops and the gas turbine exhaust gas temperaturerises so long as the operation at a constant combustion temperature ismaintained. Thereby, there is such an advantage that in any case wherethe operating condition of compressor 1 becomes unstable, feed water canbe shut off immediately with reference to the gas turbine exhaust gastemperatures.

[0302] In practical application, the gas turbine exhaust gas temperaturedetector 47 is installed in the gas turbine exhaust diffuser 8, and incase said exhaust gas temperature rises more than a predetermined limitvalue within a predetermined period of time, the control unit 35 iscaused to send a signal to the feed water flow regulating valve 22 todecrease its opening so as to decrease the quantity of water injection.Further, in case in excess of its allowable value for variation, watersupply may be shut off for protection of the main body of the gasturbine. In this case, the control unit 35 sends a closing operationsignal to the feed water shut-off valve 21. Otherwise, the feed waterpump 20 may be stopped is operation in emergency.

[0303] Monitoring of fluctuations of gas turbine exhaust gastemperatures is executed for detection of non-uniform distribution ofwater droplets having been introduced into the compressor in thecircumferential direction thereof, unstable operation of the combustorand for attainment of the safety operation of the gas turbine. In thecase of non-uniform distribution of the compressor inlet temperatures,and non-uniform distribution of water droplets having been introducedinto the compressor in the circumferential direction thereof, sincethere occur variations in quantities of air and steam to be supplied tothe combustor, stable operation of the combustor is disturbed, and itappears as a variation in turbine inlet temperatures, that is, as anincreased fluctuation in the exhaust gas temperatures.

[0304] In practical application, with reference to the gas turbineexhaust gas temperature detector 47 installed in the gas turbine exhaustdiffuser 8, when a deviation of the exhaust gas temperature exceeds thepredetermined limit value, the control unit 35 sends a signal to thefeed water flow regulating valve 22 to decrease its opening so as todecrease the quantity of water injection. Further, in case in excess ofthe allowable value for variation, water supply may be shut off forprotection of the main body of the gas turbine. In this case, thecontrol unit 35 sends a closing operation signal to feed water shut-offvalve 21. Otherwise, the feedwater pump 20 may be stopped immediately.

[0305] Thereby, upon occurrence of icing or stalling phenomena, they canbe rapidly detected, so that the soundness of the gas turbine can berapidly secured.

[0306] (7) Monitoring of bearing vibrations is executed for detection ofnon-uniformities of compressor inlet air quantities and water dropletshaving been introduced into the compressor in the circumferentialdirections thereof due to the stall phenomena within the compressor orthe icing phenomena on the compressor inlet guide vane, and forattainment of the safety operation of the gas turbine. When there occursa stalling phenomenon, even if it is a rotating stall such as to induceforced vibrations on the compressor blades, or a stall flutter to inducea self oscillation of compressor blades, it causes vibration levels ofthe rotating body to increase. Therefore, there is such an advantagethat when the operational state of compressor 1 becomes unstable, watersupply can be shut off immediately responsive to the bearing vibrations.

[0307] In practical operation, the bearing vibration detector 42 isprovided on the compressor frontal bearing 6, and bearing vibrationdetector 52 is provided on the turbine exhaust side bearing 9, and whena vibration value of said bearings rises in excess of a predeterminedlimit value, the control unit 35 is caused to send a signal to the feedwater flow regulating valve 22 to decrease its opening so as to decreasethe quantity of water injection. Further, when an allowable value forvariations is exceeded, water supply may be shut off for protection ofthe main body of gas turbine. In this case, the control unit 35 sends aclosing operation signal to the feed water shut-off valve 21. Otherwise,the feed water pump 20 may be stopped immediately.

[0308] Thereby, partial occurrence of icing or stalling phenomena can bedirectly detected. The soundness of the gas turbine can be securedagainst such phenomena.

[0309] (8) Monitoring of metal temperatures of the thrust bearings isexecuted for detection of changes in thrust forces in axial directionsof the compressor and the turbine caused by water injection, and forattainment of the safety operation of the gas turbine. By waterinjection, an interstage work distribution within the compressor iscaused to deviate from its original state of the design. Therefore, abalance between thrust forces in axial directions of the compressor andthe turbine is disrupted, thereby causing a surface pressure on thethrust bearing to increase, and thereby causing the metal temperature ofthe bearing likely to increase.

[0310] In actual operation, the metal temperature detector 41 isinstalled on the thrust bearing 5, and when the thrust bearing metaltemperature rises more than a predetermined limit value, the controlunit 35 is caused to send a signal to the feed water flow regulatingvalve 22 to decrease its opening so as to decrease the quantity of waterinjection. Otherwise, when in excess of an allowable value forvariation, water supply may be shut off for protection of the main bodyof gas turbine. In this case, the control unit 35 sends a closingoperation signal to the feed water shut-off valve 21. Otherwise, thefeed water pump 20 may be stopped of its operation immediately.Unbalance between the compressor 1 and the turbine 3 can be surelydetected, so that the soundness of the gas turbine can be surelysecured.

[0311] (9) Monitoring of fluctuations in compressor wall pressures isexecuted for detection of stalling phenomena within the compressor andfor achievement of the safety operation of the gas turbine. It isdifficult to discriminate, when its atmospheric condition corresponds toregions 2 or 3 in FIG. 6 described with reference to the secondembodiment of the invention, whether it is a stall phenomenon or anicing phenomenon simply from a compressor inlet air quantity, acompressor inlet guide vane inlet casing wall pressure, a compressordischarge pressure, a discharge temperature, a compressor adiabaticefficiency, and a gas turbine exhaust gas temperature. Further, in sucha case where there are many stall regions, and in addition, these stallregions are disposed uniformly in the circumferential directions, theymay not appear clearly as bearing vibrations. Upon occurrence of a stallphenomenon, and when it is such a forced vibration on compressor bladesdue to rotating stall, since its stall region is caused to shift towardthe circumferential direction, a pressure fluctuation involved in thestall can be detected directly.

[0312] In actual operation, the compressor wall pressure variationdetection pressure sensor 44 is installed in an intermediate stage ofthe compressor 1, and when a fluctuation value of the compressor wallpressure rises more than a predetermined limit value, the control unit35 is caused to send a signal to the feed water flow regulating valve 22to decrease its opening. Otherwise, when in excess of an allowable valuefor variations, water supply may be shut off for protection of the mainbody of gas turbine. In this case, the control unit 35 sends a closingoperation signal to the feed water shut-off valve 21. Otherwise, thefeed water pump 20 may be stopped in emergency.

[0313] Since the stalling phenomenon can be directly detected, thesoundness of the gas turbine can be surely secured.

[0314] (10) Monitoring of discharge temperatures of the compressor at aplurality of points is executed for detection of non-uniformities of thecompressor inlet air quantities and water droplets having beenintroduced into the compressor in the circumferential directions thereofdue to icing phenomena on the compressor inlet guide vane, and forattainment of the safety operation of the gas turbine. Merely from acompressor inlet temperature alone, it is difficult to detect acircumferential distribution of the water droplets having beenintroduced into the compressor. Further, as a means for detectingcircumferential non-uniformities within the compressor, this method ismore direct than by the gas turbine exhaust gas temperature and thebearing vibration.

[0315] In actual operation, a plurality of compressor discharge portiontemperature detectors 45 are installed uniformly in the circumferentialdirection on a same plane in the discharge portion of the compressor 1,and when a variation in temperatures of the compressor dischargetemperature detectors rises more than a predetermined limit value, thecontrol unit 35 is caused to send a signal to the feedwater flowregulating valve 22 to decrease its opening so as to decrease thequantity of water injection. Further, when in excess of an allowablevalue of variations, water supply may be shut off for protection of themain body of gas turbine. In this case, the control unit 35 sends aclosing operation signal to the feedwater shut-off valve 21. Otherwise,the feedwater pump 20 may be stopped of its operation immediately inemergency.

[0316] Thereby, an icing or stalling phenomenon which occurs partiallycan be suitably detected.

[0317] (11) Mismatching within the compressor is detected based on anaxial flow velocity at the compressor final stage, thereby executing asafety operation of the gas turbine. FIG. 17A depicts each velocitytriangle on compressor rotor blades in presence and absence of waterinjection in the upper stream of the compressor. FIG. 17B depicts arelationship of incident angles of the compressor rotor blades versusquantities of water droplets introduced into the compressor.

[0318] The water droplets having been introduced into the compressor arevaporized therein, absorbing heat from ambient main air stream, andlowering the temperature of the main air stream, thereby resulting in areduced volume flow rate of air. This reduced volume flow rate meansthat the axial flow velocity of the main air flow is reduced, and itseffect appears most significantly in the final stage of the compressor.When the axial flow velocity drops, an incident angle of a rotor bladein the inlet of compressor rotor blades becomes large as indicated inFIG. 17A, thereby tending easily to cause a positive stall thereof. Whena stall occurs, a substantial drop in the compressor efficiency resultsin, and in addition, a possible damage of the blade due to stall flutteris feared to take place, therefore, this occurrence must be avoidedalways in the practical operation.

[0319] Therefore, a limit value for an allowable region in which theincident angle of the compressor rotor blades is allowed to change isset up, and it is ensured that the changes of its incident angle arerestricted within a range of incident angles which is applicablecorresponding to changes of atmospheric temperatures under normaloperation. In normal operation of the compressor, when an incident angleof a compressor rotor blade n the rear stage thereof becomes maximum iswhen its atmospheric temperature becomes lowest. In this embodiment ofthe invention depicted in FIG. 17B, an incident angle at 0° C. ofatmospheric temperature is defined to be a limit value for the time ofwater injection. The axial velocity within the compressor may becalculated at any stage thereof. However, since the mismatching is mostlikely to occur in the final stage thereof, the final stage is selectedin this embodiment.

[0320]FIG. 18 indicates a control unit for detecting a mismatching inthe final stage of the compressor by detecting an axial flow velocity atthe compressor final stage, and controlling a water spray quantity ofthe spray nozzle 17 on the basis of the detected value.

[0321] The incident angle depicted in FIG. 17B may be considered to bedetermined approximately by its axial flow velocity alone provided thatthe number of revolutions is constant at its rated value. Therefore, thequantity of water is controlled such that the axial flow velocity of thefinal stage of the compressor is ensured not to drop below thepredetermined limit value, namely, for example, the axial flow velocityat 0° C. of atmospheric temperature under normal operation. Instead ofthe axial flow velocity of the final stage of the compressor, acalculated incident angle or flow efficiency may be used for control ofthe water quantity. In any case of the above methods, calculation of theaxial flow velocity becomes necessary.

[0322] The axial flow velocity at the final stage of the compressor iscalculated on the basis of a compressor outlet flow quantity Gcd, acompression outlet gas density ρ, and a compressor outlet annulus area.The compressor outlet annulus area among them is a constant value whichis determined by dimensions of each type of machines, therefore, it isonly required to calculate compressor outlet flow quantity Gcd andcompression outlet gas density ρ.

[0323] Compression outlet gas density p can be calculated if a pressure,temperature and gas constant at the outlet of the compressor are known.As its pressure and temperature, detected values of compressor dischargepressure Pcd and compressor discharge temperature Tcd may be used. Asfor gas constant Rwet, since components of the compressor outlet gasslightly differ from components of inlet dry air due to vaporization ofwater droplets within the compressor, gas constant Rwet may be obtainedby compensating gas constant Rdry of dry air with absolute humidity Xs3of the compressor discharge air. Further, in case a ratio of thequantity of water injection relative to the compressor inlet air flow issmall, since its gas constant is less influenced, gas constant Rdry ofthe dry air may be used without correction of humidity to simplify thecalculation.

[0324] Compressor outlet flow quantity Gcd is calculated by adding waterdroplet quantity Gw1 having been vaporized within the compressor tocompressor inlet wet-state air quantity Gwet. This is because that sincethe entire portion of the water droplets having been introduced into thecompressor will be fully vaporized while flowing down to the outletportion of the compressor, in order to calculate an axial flow velocityat the final stage of the compressor, it becomes necessary to take intoaccount an increase in its working gas flow quantity due to vaporizedwet contents. Further, in the case where extraction of the gas from theintermediate stage of the compressor is executed for use of cooling theturbine blades, sealing the bearing and the like, an extracted amount ofthe gas is subtracted.

[0325] Water droplet quantity Gw1 having been vaporized within thecompressor refers to the intra compressor water droplet injectionquantity described in the fourth embodiment of the invention, which iscalculated in the same manner as in the fourth embodiment. Further, thismay be substituted by the effective water injection quantity describedin the third embodiment of the invention, or an indication by waterflowmeter 23 may be used directly for simplification.

[0326] Since a compressor inlet air flow to be calculated by a normalmeasuring instrument is in a dry-state, wet-state compressor inlet airquantity Gwet is calculated by compensating for a slight difference ingas components due to vaporization of water droplets within thecompressor. For this compensation, absolute humidity Xs2 between thebottom stream of the compressor water injection unit and the upperstream of the compressor is detected, and wet-state compressor inletflow quantity Gwet is calculated using a specific gravity of the wetair. In order to simplify its calculation, a dry-state compressor inletflow quantity Gdry may be used as it is without compensation.

[0327] The control unit 35 calculates an axial flow velocity at thefinal stage of the compressor from compressor outlet flow quantity Gcdand compressor outlet gas density ρ which have been calculated, then, inthe case where its axial flow velocity is lowered more than apredetermined limit value, the control unit 35 sends a signal to thefeedwater flow regulating valve 22 to decrease its opening so as toreduce the quantity of water injection. Further, when in excess of anallowable value for variations, water supply may be shut off forprotection of the main body of gas turbine. In this case, the controlunit 35 sends a closing operation signal to the feedwater shut-off valve21. Otherwise, the feedwater pump 20 may be stopped of its operation inemergency.

[0328] Monitoring of the quantity of drain at the inlet portion of thecompressor is executed to prevent an overflow of drain into thecompressor when by any reason the drain within the intake duct fails tobe discharged, and to ensure the safety operation of the gas turbine andavoidance of wear or erosion of compressor blades.

[0329] In the case where the intake duct 13 in the upstream side of thegas turbine's compressor is located in the upper direction as indicatedin FIG. 14, if the drain outlet valves 53, 54 in a drain dischargesystem are closed by malfunction or the like, a level of drain in thecompressor intake portion will rise as high as it overflows into thecompressor unless some measure is taken. If drain is allowed to overflowinto the compressor, it may cause a serious problem such as wear of thecompressor blades, unstable operation of the compressor, an increasedcombustion vibration, a blow-off of flame in the combustor, increasedbearing vibrations and the like, and thereby resulting in a failurewhich damages the gas turbine itself.

[0330] An example of drain detection according to the invention isdepicted in FIG. 14. In the bottom portion of the compressor intakeportion, a drain discharge hole is provided, and a drain outlet pipe 50is provided with a drain slant to easily discharge the drain. The drainhaving been discharged is recovered in a drain groove. Drain leveldetector pipe 49 erecting vertically from drain outlet pipe 50 isprovided with a level switch 48. When the drain level rises above apredetermined limit value, the control unit 35 is caused to send asignal to the feed water flow regulating valve 22 to decrease itsopening so as to decrease the quantity of water injection. Further, whenin excess of an allowable value of variations, water supply may be shutoff for the protection of the main body of gas turbine. In this case,the control unit 35 sends a close operation signal to the feed watershut-off valve 21. Otherwise, the feedwater pump 20 may be stopped inemergency.

[0331] A tenth embodiment of the invention will be described withreference to FIGS. 1, 19 and 20.

[0332] Control unit controls so as to increase a fuel injection quantityto the combustor 2 when water spray quantity from the spray nozzle ismore than when small.

[0333]FIG. 19 shows an example of detecting the humidity of air suppliedto the compressor and a water spray quantity of the spray nozzle 17, andcontrolling (or compensating) a fuel injection quantity to the combustor2 based on the detected values. FIG. 20 shows an example of detectingthe compressor discharge humidity and controlling (or compensating) afuel injection quantity to the combustor 2 based on the detected values.A gas turbine exhaust gas temperature according to the absolute humidityof compressor and steam or water spray quantity of the combustor iscompensated. By changing of setting an exhaust gas temperature controlline to be higher or by compensating an exhaust gas measurement value, afuel injection quantity is increased.

[0334] It is normal for the gas turbine under a rated load to beoperated at a constant combustion temperature. However, a directmeasurement of a combustion temperature is difficult since itscombustion temperature is extremely high. Therefore, a gas turbineexhaust gas temperature is measured instead of direct measurement of thecombustion temperature. In order to maintain the combustion temperatureat a constant value, an exhaust gas temperature control line related tocompressor discharge pressures or compressor compression ratios ispredetermined, and a quantity of fuel flow is controlled so thatmeasured values are on the control line. In a gas turbine of such a typewherein water injection is carried out in the upstream side of itscompressor, an absolute humidity of air discharged from the compressorincreases more than normal due to vaporization of water within theintake duct 13 and compressor 1, thereby resulting in a change ofcomponents of the turbine inlet gas due to its increased moisturecomponent, and thereby changing a ratio of specific heat of the gasserving as a working medium within the turbine. In this case, althoughan effect of its added moisture content on the turbine efficiency issmall, a drop in the ratio of specific heat due to the changes in thegas components becomes predominant, and an attempt to maintain thecombustion temperature constantly results in an increase in its exhausttemperature.

[0335] Therefore, in actual operation of the gas turbine, if the sameexhaust temperature control line is used irrespective of a difference inratios of specific heat, operation at a combustion temperature lowerthan a design value occurs when its moisture content in the inlet of theturbine becomes large, thereby preventing the utmost utilization of theoutput improvement effect of the invention from being demonstrated.

[0336] Therefore, a control is executed so as to increase an inectionquantity of fuel into the combustor 2 when a water injection quantityfrom the spray nozzle is lager than when small.

[0337] Therefore, as indicated in FIG. 20, by measuring an absolutehumidity of a discharged air from the compressor, an exhaust gastemperature correction quantity is calculated corresponding to a changein combustion temperatures depending on its moisture content. Bysubtracting the above-mentioned exhaust gas temperature correctionquantity from an actual exhaust gas temperature having been measured, anexhaust gas temperature correction value for use in the control ofcombustion temperatures is calculated. Thereby, it becomes possible tooperate the gas turbine at a constant combustion temperature for anyquantity of water injection, thereby achieving a maximum outputargumentation effect.

[0338] Further, depending on a type of combustor, a steam injection orwater injection is executed for its combustor in order to reduce NOx.Also in this case, its wet content in the inlet of the turbineincreases, thereby changing a ratio of specific heat of the gas servingas the working medium in the turbine, and when an attempt is made tomaintain its combustion temperature at a constant value, its exhausttemperature increases. Therefore, by calculating a net absolute humidityat the turbine inlet from a sum of a steam or water injection quantityto the combustor and an absolute humidity of compressor outlet air,then, an exhaust gas temperature correction quantity corresponding to achange in combustion temperatures resulting from its wet content iscalculated. By subtracting the above-mentioned exhaust gas temperaturecorrection quantity from an actual exhaust gas temperature having beenmeasured, an exhaust gas temperature correction value for use forcontrolling combustion temperatures is calculated. Thereby, it becomespossible to operate the gas turbine at a constant combustion temperaturefor any quantity of water injection into the compressor, and for anyquantity of steam or water injection into the combustor, therebyachieving a maximum output argumentation effect.

[0339] Further, the exhaust gas temperature control line may becorrected instead of correction of measured exhaust gas temperatures.

[0340] A detection means for absolute humidities of compressor dischargeair may be the same as in the third embodiment. Further, the moisturecontent in the gas flowing into the combustor may be calculated as shownin FIG. 19, instead of the direct detection of the absolute humidity ofthe compressor discharge air, from an absolute humidity of theatmosphere under operational conditions and an effective water injectionquantity. In this case, calculation of the effective water injectionquantity is executed in the same manner as in the third embodiment ofthe invention.

[0341] An eleventh embodiment of the present invention will bedescribed, referring to FIGS. 1, 21A and 21B.

[0342] The present embodiment, basically, may have a similarconstruction to that of the first embodiment. In addition to theconstruction, a detector for detecting NOx concentration is provided onthe exhaust flow passage of the turbine 3.

[0343] By detecting NOx concentration, a water spray injection quantityfrom the spray nozzle 17 is controlled not to exceed a limit value. Anexample of the control is indicated in FIG. 7-d. In FIG. 7-d, when theNOx concentration at the gas turbine inlet is higher than a target NOxconcentration, water spray is injected to decrease the NOx concentrationto the target value. In this case, a water spray injection quantity iswithin a range which is lower than a maximum water injection instructionvalue of FIG. 7-c.

[0344] Water spray injection increases a humidity of a compressordischarge air which is a combustion air for the combustor, and has thesame effect as a NOx decreasing effect due to an increase of humiditywhich is caused by water or steam injection into the combustor. However,the method of water spray injection into the compressor lowers an airtemperature within the intake air duct and is able to increase an outputof the gas turbine by decreasing a power for the compressor.

[0345] Further, as compared with the above-mentioned NOx emissionreduction executed by the water or steam injection into the combustor,in the present embodiment, a gas that water and air inside the combustorare homogeneously mixed flows in the combustor, so that a mixingcondition of water and air is better. Therefore. NOx emission can bereduced with simple construction, suppressing combustion vibrations andmaintaining a stable combustion.

[0346] Further, In addition to the water spray injection by the spraynozzle 17, a case where a mechanism for injecting steam into thecombustor is provided is shown in FIGS. 21A and 21B.

[0347]FIG. 21A indicates a relationship between water injectionquantities and NOx concentrations in gas turbine's exhaust gas, and FIG.21B indicates a relationship between water injection quantities andcombustion vibration.

[0348] In FIGS. 21A and 21B, an operational condition with zero quantityof water injection in the upper stream of the compressor is defined tobe at point A. When a quantity of steam or water injection into thecombustor is constant, and when the quantity of water injection in theupstream side of the compressor is increased, a NOx concentration in theexhaust gas from the gas turbine decreases, however, combustionvibrations of the combustor increase. Therefore, the control unit 35 iscaused to send a signal to the feedwater flow regulating valve 22 todecrease its opening and reduce the quantity of water injection so thatthe NOx concentration and combustion vibrations will be within allowablevalues, respectively.

[0349] Otherwise, in order to hold the combustion vibrations constantwhile increasing the quantity of water infection in the upstream side ofthe compressor, the quantity of steam or water injection into thecombustor may be reduced. However, there exists a contradictingrelationship that reduction of the quantity of steam and water injectioninto the combustor will increase NOx concentration in the gas turbine'sexhaust gas. Therefore, by monitoring both the above-mentionedcombustion vibrations and the NOx concentration in the exhaust gas, andsuppressing both of them within their allowable values, the quantity ofsteam and water injection into the combustor is controlled such that thepoint of operation in FIG. 21A, 21B is caused to shift from point A topoint B, then to point C with an increasing quantity of water injection.

[0350] A twelfth embodiment of the invention will be describedhereunder, referring to FIGS. 1, 22A and 22B.

[0351] In this embodiment, a control is executed so as to change apremixed ratio of the gas turbine according to a time of water sprayinjection of a large quantity and a time of water spray injection of asmall quantity. The control is executed so as to increase a ratio ofdiffusion combustion when the water spray injection is larger than whensmall.

[0352] The present embodiment, basically, may have a similarconstruction to that of the first embodiment. In addition to theconstruction, a detector for detecting NOx concentration is provided onthe exhaust flow passage of the turbine 3, and signals are input intothe control unit 35. Further, combustion vibrations are detected and thesignal is input into the control unit 35. For example, under the normaloperational condition after starting has been completed, the controlunit 35 controls so that a diffusion combustion ratio becomes more atthe time of water spray injection than at the time of water injectionstoppage so as to decrease a NOx emission quantity, preferably tosuppress combustion vibrations in addition thereto. Further, the controlis executed so as to increase the diffusion combustion ratio when awater injection quantity is larger when small.

[0353]FIG. 22A indicates a relationship of combustor's premixturecombustion ratios versus gas turbine exhaust gas NOx concentrations, andFIG. 22B indicates a relationship of the premixture combustion ratiosversus combustion vibrations.

[0354] When a gas fuel such as a liquidified natural gas or the like isused as a fuel for the combustor, the premixture combustion anddiffusion combustion are used in combination generally. When itspremixture combustion ratio is increased with an increasing load of thegas turbine, its gas turbine exhaust gas NOx concentration is caused todrop, however, there exists a point of operation where its combustionvibration increases. Therefore, in actual operation of the gas turbine,an optimal premixture combustion ratio is set at which both the exhaustgas NOx concentration and the combustion vibration can be suppressedwithin their allowable values. Normal point of operation in the gasturbine is indicated by point A in FIG. 22A, 22B. However, in the casewhere water injection is conducted in the upstream side of thecompressor, the combustion vibration tends to occur more easily than innormal operation under the same premixture combustion ratio, therebyshifting its point of operation to point B. Therefore, in order tosuppress its combustion vibration to the same level as point A of thenormal operating point of the gas turbine, it becomes necessary todecrease its premixture combustion ratio and to increase its diffusioncombustion ratio. However, when its premixture combustion ratio isdecreased too small, the exhaust gas NOx concentration will increase.Therefore, its premixture combustion ratio is decreased to operatingpoint C at which both of the combustion vibration and the exhaust gasNOx concentration are ensured to be suppressed within their allowablevalues.

[0355] Fluid conditions change greatly by whether or not water sprayinjection is conducted and by variations in water injection quantities.However, according to the present embodiment, it is possible to causethe gas turbine to operate at a high output while maintaining thesoundness of the plant by suppressing the combustion condition to comeinto instability and suppressing variations in NOx concentration andcombustor pressure.

[0356] Water spray injection quantities or water droplet atomizingair-quantities on the upstream side of the compressor are approximatelyin proportion with supply pressures of water or atomizing air.

[0357] From the characteristics of the spray nozzle 17, a water sprayinjection quantity and water supply pressure, and atomizing air quantityand air supply pressure can be determined univocally. However, in casewhere the spray nozzle 17 is choked, an opening area reduces, so that inorder to inject the same water spray quantity, the supply pressurebecomes higher. In an actual operation, it is impossible to monitorchoking of the spray nozzle by eyes during continuous operation, achoking rate of the spray nozzle is calculated on the basis ofdeviations of supply pressure from the designed value. It is preferableto exchange the spray nozzle with another in case the choking rateexceeds a predetermined allowable value of choking rate.

[0358] Referring to FIG. 14, a drain preventing apparatus for pressuredetection piping is explained.

[0359] Of the pressure detecting piping around the gas turbine mainbody, the following needs the drain preventing means, that is, acompressor inlet total pressure pipe 39 installed on an upper portion ofthe compressor intake portion 14, a wall pressure detector 43 of acasing of the inlet of the compressor inlet guide vane 7, and acompressor discharge pressure detector 46 at the discharge portion ofthe compressor 1. In FIG. 14, only the compressor inlet total pressorpipe 39 is shown. The measuring piping 67 has a drain gradient so as toprevent drain from remaining on the way, and it is provided with a drainrecovery tank 69 at the lower portion thereof. The measuring piping 67and 68 are connected to an upper portion of the drain recovery tank 69.The measuring piping 68 connects the drain recovery tank 69 to apressure transducer 71. A drain discharge valve 70 is provided on thelower portion of the drain recovery tank 69. This embodiment also isapplied for the humidity detection piping 59 at the compressor inlet andthe humidity detecting piping 60 for compressor discharge air.

[0360] According to the present invention, a gas turbine and a controlunit which are able to improve both output and thermal efficiency bywater spray injection into the intake air introduced into the compressorinlet, along a practical operational control method can be provided.

What is claimed is:
 1. A gas turbine having a compressor for compressingan air supplied therein and discharging a compressed air, a combustorfor combusting the compressed gas from said compressor and a fuel and agas turbine to be driven by a combustion gas from said combustor,characterized by comprising: an injection unit, arranged at an upstreamside of said compressor and constructed so that water droplets aresprayed into the air to be supplied to said compressor to lower thetemperature of the air to be supplied into said compressor than anatmospheric temperature and the sprayed water droplets introduced intosaid compressor with the air having lowered in temperature areevaporated during passage through said compressor; a detection unit fordetecting the humidity of air to be supplied to said compressor; and acontrolling unit for controlling a quantity of water to be sprayed fromsaid injection unit on the basis of a signal from said detection unit.2. A gas turbine having a compressor for compressing an air suppliedtherein and discharging a compressed air, a combustor for combusting thecompressed gas from said compressor and a fuel and a gas turbine to bedriven by a combustion gas from said combustor, characterized bycomprising: an injection unit, arranged at an upstream side of saidcompressor and constructed so that water droplets are sprayed into theair to be supplied to said compressor to lower the temperature of theair to be supplied into said compressor than an atmospheric temperatureand the sprayed water droplets introduced into said compressor with theair having lowered in temperature are evaporated during passage throughsaid compressor; a detection unit for detecting the opening of acompressor inlet vane, arranged in said compressor; and a controllingunit for controlling a quantity of water to be sprayed from saidinjection unit on the basis of a signal from said detection unit.
 3. Agas turbine having a compressor for compressing an air supplied thereinand discharging a compressed air, a combustor for combusting thecompressed gas from said compressor and a fuel and a gas turbine to bedriven by a combustion gas from said combustor, characterized bycomprising: an injection unit, arranged at an upstream side of saidcompressor and constructed so that water droplets are sprayed into theair to be supplied to said compressor to lower the temperature of theair to be supplied into said compressor than an atmospheric temperatureand the sprayed water droplets introduced into said compressor with theair having lowered in temperature are evaporated during passage throughsaid compressor; and a controlling unit for controlling said injectionunit so as to stop injection of water droplets from said injection unitat the time of starting of said gas turbine and start injection of waterdroplets from said injection unit after said gas turbine has come into arated operation.
 4. A gas turbine having a compressor for compressing anair supplied therein and discharging a compressed air, a combustor forcombusting the compressed gas from said compressor and a fuel and a gasturbine to be driven by a combustion gas from said combustor,characterized by comprising: an injection unit, arranged at an upstreamside of said compressor and constructed so that water droplets aresprayed into the air to be supplied to said compressor to lower thetemperature of the air to be supplied into said compressor than anatmospheric temperature and the sprayed water droplets introduced intosaid compressor with the air having lowered in temperature areevaporated during passage through said compressor, said injection unithaving a plurality of spray nozzles for spraying water droplets; and acontrolling unit for controlling said injection unit so that the numberof said spraying nozzles spraying water droplets more than a prescribedquantity of water droplets becomes more than the number of said sprayingnozzles spraying water droplets less than the prescribed quantity ofwater droplets.
 5. A gas turbine having a compressor for compressing anair supplied therein and discharging a compressed air, a combustor forcombusting the compressed gas from said compressor and a fuel and a gasturbine to be driven by a combustion gas from said combustor,characterized by comprising: an injection unit, arranged at an upstreamside of said compressor and constructed so that water droplets aresprayed into the air to be supplied to said compressor to lower thetemperature of the air to be supplied into said compressor than anatmospheric temperature and the sprayed water droplets introduced intosaid compressor with the air having flowered in temperature areevaporated during passage through said compressor, said injection unithaving a water supply system, an air supply system and a spray nozzlefor being supplied with water and air from said water supply system andsaid air supply system and spraying water droplets; and a controllingunit for controlling the water supply quantity and air supply quantityso as to suppress variation between a ratio of water and air supplied tosaid spray nozzle when the water droplet supply quantity is small and aratio of water and air supplied to said spray nozzle when the waterdroplet supply quantity is large.
 6. A gas turbine having a compressorfor compressing an air supplied therein and discharging a compressedair, a combustor for combusting the compressed gas from said compressorand a fuel and a gas turbine to be driven by a combustion gas from saidcombustor, characterized by comprising: an injection unit, arranged atan upstream side of said compressor and constructed so that waterdroplets are sprayed into the air to be supplied to the compressor tolower the temperature of the air to be supplied into said compressorthan an atmospheric temperature and the sprayed water dropletsintroduced into said compressor with the air having lowered intemperature are evaporated during passage through said compressor, saidinjection unit having a water supply system, an air supply system and aspray nozzle for being supplied with water and air from said watersupply system and said air supply system and spraying water droplets;and a controlling unit for controlling the water supply quantity and airsupply quantity as to increase a ratio of water to air, supplied to saidspray nozzle when a spray quantity of water droplets is more, ascompared with a small spray quantity.
 7. A gas turbine having acompressor for compressing an air supplied therein and discharging acompressed air, a combustor for combusting the compressed gas from saidcompressor and a fuel and a gas turbine to be driven by a combustion gasfrom said combustor, characterized by comprising: an injection unit,arranged at an upstream side of said compressor and constructed so thatwater droplets are sprayed into the air to be supplied to the compressorto lower the temperature of the air to be supplied into said compressorthan an atmospheric temperature and the sprayed water dropletsintroduced into said compressor with the air having lowered intemperature are evaporated during passage through said compressor, saidinjection unit having a water supply system, an air supply system and aspray nozzle for being supplied with water and air from said watersupply system and said air supply system and spraying water droplets;and a controlling unit for controlling the water supply quantity and airsupply quantity so as to increase and decrease the water supply quantityaccording to an increase and a decrease of a spray quantity of waterdroplets and maintain the air supply quantity to be constant.
 8. A gasturbine having a compressor for compressing an air supplied therein anddischarging a compressed air, a combustor for combusting the compressedgas from said compressor and a fuel and a gas turbine to be driven by acombustion gas from said combustor, characterized by comprising: aninjection unit, arranged at an upstream side of said compressor andconstructed so that water droplets are sprayed into the air to besupplied to the compressor to lower the temperature of the air to besupplied into said compressor than an atmospheric temperature, thesprayed water droplets introduced into said compressor with the airhaving lowered in temperature are evaporated during passage through saidcompressor and said injection unit having a water supply system, an airsupply system and a spray nozzle for being supplied with water and airfrom said water supply system and said air supply system and sprayingwater droplets; and a controlling unit for controlling said injectionunit so as to start to supply air to said spray nozzle first and thenstart to supply water to said spray nozzle, thereby to start spraying ofwater droplets.
 9. A gas turbine having a compressor for compressing anair supplied therein and discharging a compressed air, a combustor forcombusting the compressed gas from said compressor and a fuel and a gasturbine to be driven by a combustion gas from said combustor,characterized by comprising: an infection unit, arranged at an upstreamside of sand compressor and constructed so that water droplets aresprayed into the air to be supplied to the compressor to lower thetemperature of the air to be supplied into said compressor than anatmospheric temperature and the sprayed water droplets introduced intosaid compressor with the air having lowered in temperature areevaporated during passage through said compressor, said injection unithaving a water supply system, an air supply system and a spray nozzlefor being supplied with water and air from said water supply system andsaid air supply system and spraying water droplets; and a controllingunit for controlling said injection unit so that the water dropletspraying is stopped by decreasing a quantity of air supplied to saidspray nozzle first and then decreasing a quantity of water supplied tosaid spray nozzle.
 10. A gas turbine having a compressor for compressingan air supplied therein and discharging a compressed air, a combustorfor combusting the compressed gas from said compressor and a fuel and agas turbine to be driven by a combustion gas from said combustor,characterized by comprising: an injection unit, arranged at an upstreamside of said compressor and constructed so that water droplets aresprayed into the air to be supplied to the compressor to lower thetemperature of the air to be supplied into said compressor than anatmospheric temperature and the sprayed water droplets introduced intosaid compressor with the air having lowered in temperature areevaporated during passage through said compressor; and a controllingunit for controlling said injection unit so as to first issue a signalfor stopping the water droplet spraying and then issue an instruction todecrease the compressor inlet guide vane opening on the basis of a gasturbine trip signal, during operation of said injection unit.
 11. A gasturbine having a compressor for compressing an air supplied therein anddischarging a compressed air, a combustor for combusting the compressedgas from said compressor and a fuel and a gas turbine to be driven by acombustion gas from said combustor, characterized by comprising: aninjection unit, arranged within an intake air duct at an upstream sideof said compressor and constructed so that water droplets are sprayedinto the air to be supplied to the compressor to lower the temperatureof the air to be supplied into said compressor than an atmospherictemperature and the sprayed water droplets introduced into saidcompressor with the air having lowered in temperature are evaporatedduring passage through said compressor; and a controlling unit, having aplurality of air temperature detectors arranged in said intake air ductin a peripheral direction, for controlling said injection unit so as todecrease a quantity of water spray when a deviation in detected valuereaches to a prescribed value, during operation of spraying waterdroplets.
 12. A gas turbine having a compressor for compressing an airsupplied therein and discharging a compressed air, a combustor forcombusting the compressed gas from said compressor and a fuel and a gasturbine to be driven by a combustion gas from said combustor,characterized by comprising: an injection unit, arranged within anintake air duct at an upstream side of said compressor and constructedso that water droplets are sprayed into the air to be supplied to thecompressor to lower the temperature of the air to be supplied into saidcompressor than an atmospheric temperature and the sprayed waterdroplets introduced into said compressor with the air having lowered intemperature are evaporated during passage through said compressor; and acontrolling unit for controlling said injection unit so as to monitor aflow rate by weight of air introduced into said compressor and decreasea quantity of water spray when the flow rate reaches to a prescribedvalue, during operation of spraying water droplets.
 13. A gas turbinehaving a compressor for compressing an air supplied therein anddischarging a compressed air, a combustor for combusting the compressedgas from said compressor and a fuel and a gas turbine to be driven by acombustion gas from said combustor, characterized by comprising: aninjection unit, arranged within an intake air duct at an upstream sideof said compressor and constructed so that water droplets are sprayedinto the air to be supplied to the compressor to lower the temperatureof the air to be supplied into said compressor than an atmospherictemperature and the sprayed water droplets introduced into saidcompressor with the air having lowered in temperature are evaporatedduring passage through said compressor; a detection unit for detectingthe pressure of a casing wall of an inlet guide vane portion of saidcompressor; and a controlling unit for controlling a quantity of waterspray on the basis of the detected wall pressure, during operation ofspraying water droplets.
 14. A gas turbine having a compressor forcompressing an air supplied therein and discharging a compressed air, acombustor for combusting the compressed gas from said compressor and afuel and a gas turbine to be driven by a combustion gas from saidcombustor, characterized by comprising: an injection unit, arrangedwithin an intake air duct at an upstream side of said compressor andconstructed so that water droplets are sprayed into the air to besupplied to the compressor to lower the temperature of the air to besupplied into said compressor than an atmospheric temperature and thesprayed water droplets introduced into said compressor with the airhaving lowered in temperature are evaporated during passage through saidcompressor; and a controlling unit for controlling said injection unitso as to monitor a discharge pressure of said compressor and decrease aquantity of water spray when the discharge pressure becomes less than aprescribed value, during operation of spraying water droplets.
 15. A gasturbine having a compressor for compressing an air supplied therein anddischarging a compressed air, a combustor for combusting the compressedgas from said compressor and a fuel and a gas turbine to be driven by acombustion gas from said combustor, characterized by comprising: aninjection unit, arranged within an intake air duct at an upstream sideof said compressor and constructed so that water droplets are sprayedinto the air to be supplied to the compressor to lower the temperatureof the air to be supplied into said compressor than an atmospherictemperature and the sprayed water droplets introduced into saidcompressor with the air having lowered in temperature are evaporatedduring passage through said compressor; and a controlling unit formonitoring an adiabatic efficiency of said compressor and controlling aquantity of water spray on the basis of the adiabatic efficiency, duringoperation of spraying water droplets.
 16. A gas turbine having acompressor for compressing an air supplied therein and discharging acompressed air, a combustor for combusting the compressed gas from saidcompressor and a fuel and a gas turbine to be driven by a combustion gasfrom said combustor, characterized by comprising: an injection unit,arranged within an intake air duct at an upstream side of saidcompressor and constructed so that water droplets are sprayed into theair to be supplied to the compressor to lower the temperature of the airto be supplied into said compressor than an atmospheric temperature andthe sprayed water droplets introduced into said compressor with the airhaving lowered in temperature are evaporated during passage through saidcompressor; and a controlling unit for monitoring an exhaust gastemperature and controlling a quantity of water spray on the basis ofthe exhaust gas temperature, during operation of spraying waterdroplets.
 17. A gas turbine having a compressor for compressing an airsupplied therein and discharging a compressed air, a combustor forcombusting the compressed gas from said compressor and a fuel and a gasturbine to be driven by a combustion gas from said combustor,characterized by comprising: an injection unit, arranged within anintake air duct at an upstream side of said compressor and constructedso that water droplets are sprayed into the air to be supplied to thecompressor to lower the temperature of the air to be supplied into saidcompressor than an atmospheric temperature and the sprayed waterdroplets introduced into said compressor with the air having lowered intemperature are evaporated during passage through said compressor; and acontrolling unit for monitoring vibrations of a gas turbine bearing andcontrolling a quantity of water spray on the basis of the vibrationvalue, during operation of spraying water droplets.
 18. A gas turbinehaving a compressor for compressing an to air supplied therein anddischarging a compressed air, a combustor for combusting the compressedgas from said compressor and a fuel and a gas turbine to be driven by acombustion gas from said combustor, characterized by comprising: aninjection unit, arranged within an intake air duct at an upstream sideof said compressor and constructed so that water droplets are sprayedinto the air to be supplied to the compressor to lower the temperatureof the air to be supplied into said compressor than an atmospherictemperature and the sprayed water droplets introduced into saidcompressor with the air having lowered in temperature are evaporatedduring passage through said compressor; and a controlling unit formonitoring a thrust bearing metal temperature of said gas turbine andcontrolling a quantity of water spray on the basis of the thrust bearingmetal temperature, during operation of spraying water droplets.
 19. Agas turbine having a compressor for compressing an air supplied thereinand discharging a compressed air, a combustor for combusting thecompressed gas from said compressor and a fuel and a gas turbine to bedriven by a combustion gas from said combustor, characterized bycomprising: an injection unit, arranged within an intake air duct at anupstream side of said compressor and constructed so that water dropletsare sprayed into the air to be supplied to the compressor to lower thetemperature of the air to be supplied into said compressor than anatmospheric temperature and the sprayed water droplets introduced intosaid compressor with the air having lowered in temperature areevaporated during passage through said compressor; and a controllingunit for monitoring an axial flow velocity of fluid flowing in saidcompressor and controlling a quantity of water spray on the basis of theaxial flow velocity, during operation of spraying water droplets.
 20. Agas turbine having a compressor for compressing an air supplied thereinand discharging a compressed air, a combustor for combusting thecompressed gas from said compressor and a fuel and a gas turbine to bedriven by a combustion gas from said combustor, characterized bycomprising: an injection unit, arranged within an intake air duct at anupstream side of said compressor and constructed so that water dropletsare sprayed into the air to be supplied to the compressor to lower thetemperature of the air to be supplied into said compressor than anatmospheric temperature and the sprayed water droplets introduced intosaid compressor with the air having lowered in temperature areevaporated during passage through said compressor; and a controllingunit for controlling said injection unit so as to increase a quantity offuel supplied to said combustor at time of water droplet spraying, ascompared with a quantity of fuel supplied to said combustor at time ofstopping of water droplet spraying.
 21. A gas turbine having acompressor for compressing an air supplied therein and discharging acompressed air, a combustor for combusting the compressed gas from saidcompressor and a fuel and a gas turbine to be driven by a combustion gasfrom said combustor, characterized by comprising: an injection unit,arranged within an intake air duct at an upstream side of saidcompressor and constructed so that water droplets are sprayed into theair to be supplied to the compressor to lower the temperature of the airto be supplied into said compressor than an atmospheric temperature andthe sprayed water droplets introduced into said compressor with the airhaving lowered in temperature are evaporated during passage through saidcompressor; an detection unit for detecting NOx concentration in theexhaust gas; and a controlling unit for controlling a quantity of waterspray on the basis of the detected NOx concentration.
 22. A gas turbinehaving a compressor for compressing an air supplied therein anddischarging a compressed air, a combustor for combusting the compressedgas from said compressor and a fuel and a gas turbine to be driven by acombustion gas from said combustor, characterized by comprising: apremixer provided in said combustor for burning premixed gas formed bypremixing fuel and air; an injection unit, arranged within an intake airduct at an upstream side of said compressor and constructed so thatwater droplets are sprayed into the air to be supplied to the compressorto lower the temperature of the air to be supplied into said compressorthan an atmospheric temperature and the sprayed water dropletsintroduced into said compressor with the air having lowered intemperature are evaporated during passage through said compressor; and acontrolling unit for monitoring an adiabatic efficiency of saidcompressor and controlling a quantity of water spray on the basis of theadiabatic efficiency, during operation of spraying water droplets.